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IM300/M Series 3 Plus Modbus Referencemanual

Series 3 Plus

Modbus Reference

Publication IM300/M (6.2.1)

Product Version: All

May 2009
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1987-1998, Compressor Controls Corporation. All rights reserved.

This manual is for the use of Compressor Controls Corporation and isnot to be reproduced without written permission.

Air Miser, Guardian, Recycle Trip, Reliant, Safety On, SureLink, TTC,

Total Train Control, TrainTools, TrainView, TrainWare, Vanguard,Vantage, WOIS, and the TTC and impeller logos are registered trade-

marks; and COMMAND, TrainPanel, and the Series 5 logo aretrademarks of Compressor Controls Corporation. Other company andproduct names used herein are trademarks or registered trademarks

of their respective holders.

The control methods and products discussed in this manual may be

covered by one or more of the following patents, which have beengranted to Compressor Controls Corporation by the United StatesPatent and Trademark Office:

4,949,276 5,347,467 5,508,943 5,609,4655,622,042 5,699,267 5,743,715 5,752,378

5,879,133 5,908,462 5,951,240 5,967,7426,116,258 6,217,288 6,317,655 6,332,336

6,494,672 6,503,048

Many of these methods have also been patented in other countries,and additional patent applications are pending.

The purpose of this manual is only to describe the configuration and

use of the described products. It is not sufficiently detailed to enableoutside parties to duplicate or simulate their operation.

The completeness and accuracy of this document is not guaranteed,and nothing herein should be construed as a warranty or guarantee,expressed or implied, regarding the use or applicability of the

described products. CCC reserves the right to alter the designsor specifications of its products at any time and without notice.

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Series 3 Plus Modbus Reference

3

IM300/M (6.2.1)

Document Scope

This manual describes the Series 3 Plus implementation of the Modicon Modbus

RTU Protocol. It is intended to provide the basic information necessary to integrate

such controllers into a supervisory or distributed control system (DCS).

Chapter 1 provides installation, configuration, and troubleshooting instructionsfor the Series 3 Plus Modbus serial ports..

Chapter 2 describes the basic Modbus transactions, data types, and functionssupported by Series 3 Plus Controllers.

Appendix A describes the Modbus configuration and test procedures that can beexecuted from the Engineering Panel.

The following data sheets, which are included at the back of this manual, list the

specific data points supported by each controller:

DS301/M lists the Antisurge Controllers Modbus bits and registers.

DS302/M lists the Performance Controllers Modbus bits and registers.

DS303/M lists the Dual-Loop A/P Controllers Modbus bits and registers.

DS307/M lists the Speed Controllers Modbus bits and registers.

DS308/M lists the Extraction Controllers Modbus bits and registers.

DS311/M lists the Multi-Shaft Industrial Gas Turbine Fuel ControllersModbus bits and registers.

DS312/M lists the Aero-Derivative Gas Turbine Fuel Controllers Modbus bitsand registers.

DS313/M lists the Single-Shaft Gas Turbine Fuel Controllers Modbus bits andregisters.

Each is cross-referenced to the relevant sections of the corresponding controller

instruction manuals.

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4

Contents

May 2009

The document title appears in the header of each odd-numberedpage, while the chapter or appendix title appears in the header ofeven-numbered pages. Odd-page footers list the document number

and revision level [IM300/M (6.2.1)], while even-page footers pro-vide the publication date (May 2009).

Acronyms are defined in the sections of this manual that discuss thecorresponding subjects, by placing them in parentheses followingthe spelled-out terms they represent. As an example, a three-letteracronym (TLA) is a way to represent a three-word subject by com-bining and capitalizing the initial letters of those three words. Mostare also listed under Symbols and Acronymson page 6.

Cross-references to other documents specify a section and chapter,while cross-references between chapters of this document specify apage number. References that do not specify a location are internalto the chapter in which they appear. In computerized versions of thismanual, all such references are hot-linked to their target locationsand appear in green. Entries in the tables of contents, illustrationand table lists, and index are also hot-linked but are not green.

Attention may be drawn to information of special importance byusing this text stylingor one of the following structures:

Note:

Notes contain important information that needs to be emphasized.

Caution:

Cautions contain instructions that, if not followed, could lead to irre-

versible damage to equipment or loss of data.

Warning!

Warnings contain instructions that, if not followed, could leadto personal injury.

The appearance of this electrical hazard warning symbol on CCCequipment or the word Warningappearing in this manual indicatesdangerously-high voltages are present inside its enclosure. Toreduce the risk of fire

or electrical shock, do not open the enclo-sure or attempt to access areas where you are not instructed to do

so. Refer all servicing to qualified service personnel.The appearance of this user caution symbol on CCC equipment orthe word Caution appearing in this manual indicates damage to theequipment or injury to the operator could occur if operational proce-dures are not followed. To reduce such risks, follow all proceduresor steps as instructed.

Document Conventions

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IM300/M (6.2.1)

Table of Contents

Document Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Document Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Table of Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

List of Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Symbols and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Chapter 1 Serial Ports

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7RS-232 Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Modbus TCP Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Serial Port Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Termination Resistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Surge Suppression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11ID Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Computer Inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Register Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Serial Communication Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Serial Port Activity Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Chapter 2 Protocol Description

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Transactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Message Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Exception Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Binary Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Numeric Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Read Coil Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Read Input Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Read Holding Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Read Input Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Force Single Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Preset Single Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Loopback Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Appendix A Configuration and Testing

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Glossary/Index

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
http://-/?-http://-/?-http://-/?-http://-/?-

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Contents

May 2009

List of Figures

Figure 1-1 Port 3 and 4 terminals on standard Back Panels . . . . . . . . . . . . . . . . .7Figure 1-2 Connecting to an RS-422/485 host port . . . . . . . . . . . . . . . . . . . . . . . .7Figure 1-3 Connecting to an RS-232 host port . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Figure 1-4 FTA Serial port features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Figure 1-5 Terminating resistor DIP switch on the CPU PCB. . . . . . . . . . . . . . . .10

Figure 2-1 Format of a Modbus message frame. . . . . . . . . . . . . . . . . . . . . . . . . .15Figure 2-2 Illegal request and exception response. . . . . . . . . . . . . . . . . . . . . . . .17

List of Tables

Table 1-1 Serial Port 3 and 4 data transmission parameters . . . . . . . . . . . . . . .11

Table 2-1 Supported Modbus exception codes . . . . . . . . . . . . . . . . . . . . . . . . . .16

Table 2-2 Supported Modbus data types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Symbols and Acronyms

CCC Compressor Controls Corporation

CRC Cyclic Redundancy Checksum

DCS Distributed Control System

DIP Dual Inline Package

FIM Field Input ModuleFIOM Field Input/Output Module

FOM Field Output Module

FTA Field Termination Assembly

Gnd Ground

IP Internet Protocol

RTU Remote Terminal Unit

Rx Receiver

TCP Transmission Control Protocol

TTC Total Train Control

Tx Transmitter

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7

IM300/M (6.2.1)


Chapter 1 Serial Ports

This chapter provides installation, configuration, and troubleshoot-ing instructions for the Series 3 Plus Modbus serial ports.

Figure 1-1 Port 3 and 4 terminals on standard Back Panels

Installation

Modbus communications can be implemented via either or both ofthe Port 3 and Port 4 communication channels. The Back Panel wir-ing terminals for these ports are shown in Figure 1-1, while those onthe Field Termination Assemblies (FTAs) are shown in Figure 1-4.

These ports conform to the EIA RS-485 electrical standards, whichcan provide reliable multi-dropped communications in areas withhigh levels of electrostatic or electromagnetic noise. Cable runs of

up to 4000 feet (1200 meters) are supported.These ports can be directly connected to a hosts RS-422 or RS-485serial port using either a two-wire or four-wire connection (as shownin Figure 1-2). You should use Belden 8723 twisted-pair cable (or itsequivalent), and ground the shield at one end only.

Figure 1-2 Connecting to an RS-422/485 host port

43

TB6

PORT 4

+ + RX4TX4

PORT 3

+ + RX3TX3

Tx/Rx +

Tx/Rx

Ground

Tx +

Tx

Gnd

Rx +

Rx

Tx +

Tx

Gnd

Rx +

Rx

Rx +

Rx

Ground

Tx +

Tx

Gnd

Rx +

Rx

Tx +

Tx

Gnd

Rx +

Rx

Tx +

Tx

ControllersHost ControllersHost

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Chapter 1: Serial Ports

May 2009

Figure 1-3 Connecting to an RS-232 host port

The Field Input/Output Module (FIOM) for Compressor Controllersprovides several convenient serial port wiring features, includingDB9 connectors for Ports 3 and 4 and a ribbon-cable Serial Port Busfor interconnecting the ports of all the controllers in a control panel.

RS-232Converter

If your host is equipped with serial ports conforming to the morecommon RS-232C standard, you should connect them to the con-trollers using an RS-485/232 converter with isolated grounds (forexample, the AEG OIC-422). Suitable converters can be purchasedfrom Compressor Controls Corporation.

Because Series 3 Plus Controllers do not support any handshakingsignals (such as Request-To-Send/Clear-To-Send), it may be nec-essary to cross-connect those of the host computer. A typical wiringdiagram for this application is shown in the left panel of Figure 1-3.

In an emergency (say your converter fails and you can not wait for areplacement), you can directly connect a controllers RS-422 port toa computers RS-232 port as shown in the right panel of Figure 1-3.You can not connect very many controllers at a time, and you cannot use very long cables, but you can often make it work in a pinch.

Modbus TCPConverter

Although Series 3 Plus Controllers do not have ethernet ports, oneor more Modbus TCP masters (clients) can be connected to each oftheir Modbus RTU ports via commercially-available Modbus TCP toRTU converters. This can simplify and reduce the cost of wiring PCs

and other master devices to them.

Rx +

Rx

Tx +

Tx

Gnd

2

3

4

5

6

7

8

20

+

+

G

TxD

RxD

RTS

CTS

DSR

GND

DCD

DTR

3

2

7

8

6

5

1

4

9 25

2

3

4

5

6

7

8

20

pinpin

Rx +

Rx

Tx +

Tx

Gnd

ConverterHost ControllerController

TxD

RxD

RTS

CTS

DSR

GND

DCD

DTR

3

2

7

8

6

5

1

4

9 25

2

3

4

5

6

7

8

20

pinpin Host

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9

IM300/M (6.2.1)

Figure 1-4 FTA Serial port features

Serial Port Bus

The Field Input/Output Module (FIOM) has ribbon cable connectorsfor connecting the serial ports of a group of controllers mounted inthe same control panel (see Figure 1-4).

This serial port bus is cabled by connecting the Bus Output (J5)connector of each controllers FTA to the Bus Input (J4) connectorof the next FTA. If the bus is to include controllers in more thanone panel, twisted pair cables should be used to connect the TB1through TB4 terminal blocks of the last controller in each panel tothose of the first controller in the next panel.

Each Modbus network on the bus can be divided into segments byremoving the corresponding configuration header (JB12 for Port 3,JB13 for Port 4) from the FIOM for the last controller in each seg-ment. (If the last controller is connected to the next via their terminalblocks, omit that ports twisted pair connection.)

A Modbus host can be linked into each Port 3 network segment byconnecting it to the TB3 terminal block or J2 connector for the firstcontroller in that segment. Similarly, a host can be linked into a Port4 network segment by connecting it to the first controllers TB4 ter-minal block or J3 connector.

Port 4 Port 3

JB12 JB13

Resistor Switches

Serial Bus In Serial Bus Out Port 3 DB9 Port 4 DB9

FIOM FOM

Port 4

Port 3

Note:

The serial ports of any two controllers should be interconnectedusing either the ribbon cable connectors (J4 to J5) or twisted pairterminal blocks (TB1 through TB4) but not both

.

Do not form loops by connecting the serial ports of the last controlleron a network segment to those of the first.

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10


May 2009

Figure 1-5 Terminating resistor DIP switch on the CPU PCB

TerminationResistors

The controllers RS-422 circuitry supports the parallel connection ofup to 30 multiple devices. Such a network can experience reliabilityproblems (caused by reflected signals) if there is not enough resis-tance in the circuit. Although this is not a concern when connecting

our controllers to each other, problems can occur when connectingthem to other devices.

The receiving circuit of each serial port on the CPU PCB includes a250 ohm terminating resistor that can be included or removed fromthe circuit by setting the corresponding DIP switch (see Figure 1-5).Closing a switch connects the resistor to its network, opening it dis-connects the resistor.

Controllers are shipped with all of these switches open, and we rec-ommend you leave them in that position. If you do experienceproblems, closing the terminating resistor DIP switch for the first or

last receiver on the network (or both) might solve them. Assistancein solving such problems can be obtained by calling CompressorControls Corporation.

The Field Input/Output Module (FIOM) provides a similar but moreconvenient set of termination resistors (see Figure 1-4) that shouldbe used for controllers equipped with that FTA. The internal resis-tors should then be disabled via their CPU board switches.

SurgeSuppression

Serial port voltage spikes (especially on Ports 3 and 4) can disruptthe normal functionality of the I/O processor. That can disable thediscrete inputs, Modbus ports, and communication with the FrontPanel, which causes the Fault LED to light and all other front-panelLEDs and readouts to go blank.

The potential for such malfunctions can be minimized by installingvoltage surge suppressors in all susceptible serial port circuits, andconnecting their shield grounds only at the controller end. For moreinformation, please refer to our technical note on

Transient VoltageProtection for Series 3 Plus Controllers

[TN23].

OPEN

1 2 3 4 5 6

1 2 3 4 5 6
http://../TechNotes/TN23.pdfhttp://../TechNotes/TN23.pdfhttp://../TechNotes/TN23.pdfhttp://../TechNotes/TN23.pdfhttp://../TechNotes/TN23.pdf

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11

IM300/M (6.2.1)

Configuration

Each Series 3 Plus Controller is adapted to its specific applicationby setting its configuration parameters. When setting up a control-lers Modbus ports, you must configure their data formats, assign itsnetwork identity, enable or disable Modbus read/write or read-onlyaccess, and define the register scaling range for Port 3.

All of these can be configured by setting configuration parametersfrom the Engineering Panel (located behind the Front Panel). Some,but not all, can also be set from an computer workstation running aSeries 3 Plus Configurator utility program.

Appendix Aillustrates the Engineering Panel key sequences for theparameters mentioned in this manual. You must enter the EnableReconfiguration

[MODE LOCK 5 1]sequence before you canchange any parameter values from the Engineering Panel.

Data Format

Series 3 Plus Controllers must be setup to use the same data trans-mission format as the devices they communicate with. As listed in

Table 1-1, all but two aspects of the Port 3 and Port 4 formats arefixed. The two that are not are set by the following parameters:

The Port 3 Baud Rate

and Port 3 Parity

[MODE:D COMM 3]

The Port 4 Baud Rate

and Port 4 Parity

[MODE:D COMM 4]

Using a computer workstation to reconfigure the port connecting thecontroller to that computer will obviously disrupt communicationbetween them until the computers ports are also reconfigured.

Table 1-1 Serial Port 3 and 4 data transmission parameters

ID Number

The Modbus address of a Series 3 Plus Controller is set by theComputer ID Number

[MODE COMM 0 ], which applies to Ports 2,3, and 4 and can only be changed from the Engineering Panel.

In general, each device must have a unique address. However, in aredundant Series 3 Plus Control System, each controller and itson-line backup can be given the same Computer ID Number

if youdisable Modbus While Tracking

[MODE:D LOCK 0]in both of them.In this case, only the active controller will respond to data requestsfrom the host, which would then be unable to monitor the backup.

Parameter Value

Baud Rate 4800, 9600, 19.2 kps

Start Bits 1

Data Bits 8

Stop Bits 1

Parity Even, Odd, None

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12


May 2009

To enable host access to both the active and backup controller, youmust enable Modbus While Tracking

in both of them.

Computer Inhibit

At times, it may be desirable to limit Modbus access to Series 3 PlusControllers. Thus, they have two parameters (

Read and Write Inhibit

[MODE:D LOCK 1]and Write Inhibit Only

[MODE:D LOCK 2]) thatenable you to either partially or completely disable host access viathe Modbus serial ports:

To block all Modbus access, enable Read and Write Inhibit

[LOCK 1 On]. Write Inhibit Only

[LOCK 2] is then ignored.

To allow a Modbus host to monitor but not control the controller,disable Read and Write Inhibit

and enable Write Inhibit Only

[LOCK 1 Off, LOCK 2 On].

To provide unlimited host access, disable both Read and WriteInhibit

and Write Inhibit Only

[LOCK 1 and LOCK 2 Off].

Register Scaling As discussed on page 18, a Series 3 Plus Controller can be config-ured to scale register values communicated via Port 3 using eitherthe full ranges (for example, 0 to 102.4 percent) listed in the Modbusdata tables or a slightly smaller range (0 to 100 percent) compatiblewith some older PLCs. This is done by setting the Modbus RegisterScaling[MODE:D LOCK 7]parameter.

Note:In an application using load-sharing or pressure-override control(which use Port 2), changing a controllers Computer ID Numbermight require changes to the configuration parameters of its com-

panion controllers as well as to your Modbus host programs.

Note:

Enabling Read and Write Inhibitblocks all Modbus communication,thus precluding the use of any software support program (for exam-ple, Toolbox or COMMAND).

Enabling Write Inhibit Onlyprevents the host from writing to Modbusregisters and coils only. Although this does not stop support pro-

grams from downloading parameters or controller software, it doesprevent them from changing any variables (such as the limiting con-trol thresholds) that are accessed via such coils or registers.

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Series 3 Plus Modbus Reference 13

IM300/M (6.2.1)

Troubleshooting Series 3 Plus Controllers offer several features that can prove usefulwhen trouble-shooting serial communications problems.

If you do experience such difficulties, you should make sure that noduplicate controller ID numbers have been assigned, that all of themagree with those used in your host program, and that computercommunications were not inadvertently inhibited in any controllers.

Make sure the Data Format(see page 11)of the controllers andhost agree. If they do and you are experiencing Serial Communica-tion Errors, you may need to enable the Termination Resistors(seepage 10)in one or more controllers, most likely the last one in adaisy-chained network.

Some hosts, particularly older PLCs, may experience frequentsynchronization errors at high baud rates. Thus, communicationproblems can sometimes be solved by reducing that rate.

SerialCommunicationErrors

Series 3 Plus Controllers indicate the occurrence of serial communi-cation errors by beeping and displaying a message of the followingform on the engineering panel:

Where the number in the fourth field identifies the Port on which theerror was detected (1 through 4) and the P, O, and Fcharactersappear only if the corresponding type of error occurred:

The Pwill be lit if a parity error was detected. This indicates thatthe number of set bits (ones) in a received character did notagree with the defined parity for the serial port it arrived on.Continuous parity errors often indicate that you need to changea parity setting in either the transmitting or receiving device.

The Owill be lit if an overrun error occurred. This means that thecontroller failed to read an incoming character before the nextone arrived.

The Fwill be lit if a framing error was detected. This indicatesthat the controller was unable to decode an incoming characterdue to a synchronization error. Continuous framing errors oftenindicate that the baud rates of the sending and receiving device

disagree.

The most common cause of frequent or continuous errors is faultywiring. Other possible causes of serial communication errors includeline noise, improper configuration, and power interruptions. How-ever, absence of an error display does not verify normal functioningof the serial communication channels. For example, no errors aredisplayed if serial communication is not working at all. However, the

Com4 POF

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14 Chapter 1: Serial Ports

May 2009

ComErr LED would reveal such a problem if it prevented the recep-tion of required information.

Because the communication protocols employed by the controllerreject faulty messages (and usually provide for their re-transmis-sion), isolated errors rarely affect the operation of the controller.

Serial PortActivity Test

The Serial Port Activity Test[MODE TEST 3]will elicit a dynamicdisplay that reveals whether the specified serial port is transmittingor receiving data (Port 3 in this example):

The bar after the Rwill be in the high position if the selected port iscurrently receiving a transmission, otherwise it will be low. Similarly,the bar after the Twill be high only when that port is transmitting. Inthe above example, Port 3 is receiving but not transmitting.

Note: If a communication error occurs while you are entering parametervalues, the controller will only beep.

PT3 R-T_

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IM300/M (6.2.1)


Chapter 2 Protocol DescriptionThis chapter describes the basic Modbus transactions, data types,and functions supported by Series 3 Plus Controllers.

Transactions The Modbus RTU protocol defines a method of digital informationexchange for devices on a shared serial communications line.Under this protocol, one device must be designated as the masterand all others as slaves (because Series 3 Plus Controllers cannotbe masters, we also refer to the master as the host and the slavesas controllers). A transaction consists of a single request from thehost to a specific controller and a single response from that device.

Both of these Message Framesmust conform to a specific format.Synchronizationis achieved by limiting the elapsed time betweenthe bytes that comprise each frame. If a controller cannot comply

with a request, it returns an Exception Responseto the host.

Figure 2-1 Format of a Modbus message frame

Message Frames As shown in Figure 2-1and described below, each message frameconsists of a series of bytes grouped into Address, Function, Data,and Error-Checkfields.

Address The first field in each frame is the device address byte. In a request,this identifies the device to which the query is being directed. In aresponse, it is the address of the responding device. For a Series 3Plus Controller, this address is defined by the Computer ID Number[MODE COMM 0 ]parameter.

Function The second field in each frame is the function byte. In a request, itspecifies the function the controller is to perform. If that device is

able to perform the requested function, its response will echo therequested function code. Otherwise, it will signal an ExceptionResponse(see page 16)by setting the most-significant bit of therequested function code to one and returning the result.

Data The third field in a message frame is the data field, which varies inlength according to the function. In a host request, this field containsinformation the controller may need to complete the requested func-tion. In a response, it contains any data requested by the host.

1 byte 1 byte variable

Address

Field

Function

Field

2 bytes

Error

Check

Field

Data

Field

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Error-Check The last two bytes in a message frame comprise a standard CyclicRedundancy Checksum (CRC-16) calculated from the first threefields of the message frame. This can be used to determine if themessage has been corrupted during transmission.

Because the CRC-16 function is widely used and described innumerous publications, it is not described in this document. ContactCompressor Controls Corporation for assistance if you cannotlocate a suitable reference.

Synchronization In order to achieve reliable communication, the receiving devicemust be able to identify the start of a new message. The ModbusRTU protocol used by Series 3 Plus Controllers provides this syn-chronization by limiting the idle time between successive characterswithin a frame. If the controller fails to detect the next character of amessage within three character times (about three milliseconds at9600 baud), that message is flushed and the next byte received is

interpreted as the address field of a new message frame.

ExceptionResponse

Request frames containing parity or checksum errors are ignored no response is sent by any device. If an otherwise valid requestframe contains an illegal request (one not supported by the targetcontroller), an exception response will be returned to the host.

The four fields of an exception response contain:

the address of the responding controller,

the requested function with its most-significant bit set to one,

an appropriate exception code, and the CRC-16 checksum.

Table 2-1lists the various exception codes which may be returnedby a Series 3 Plus Controller. Prior to the XX6-004 control programrevisions, a NAK response was returned if an attempt was made toset a controllers output while it was operating automatically.

Table 2-1 Supported Modbus exception codes

Code Name Description

01 Illegal Function Requested function not supported

02Illegal DataAddress

Requested data address not supported

03 Illegal Data Value Specified data value not supported

07 NAK (Negative)Requested function prohibited by Write InhibitOnly[MODE:D LOCK 2]or Read and WriteInhibit[MODE:D LOCK 1]setting.

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Figure 2-2 Illegal request and exception response

Figure 2-2illustrates an illegal request and the correspondingexception response. In this example, the host asks the controller toread the status of eight coils beginning at offset 0201H (coils 514 to521). The illegal address exception code (02) indicates those coilsare not supported by the controller.

Data Types Series 3 Plus Modbus data points are referenced in the same man-

ner as in Modicon PCs: coils and discrete inputs have Binary Values

input and holding registers have Numeric Values.

Each function references only one type of data. This allows mes-sage frames to reference data points by their offsets from the lowestpossible address for that type of data. For example, holding register40009 is referenced by its offset (8) from register 40001.

Table 2-2lists the address ranges and offsets for the supported datatypes, as well as the functions that apply to each. Each controllersModbus data sheet lists and describes the data it supports.

Table 2-2 Supported Modbus data types

01 01

Address

Function

Code

Number

ofPoints

CRC

Starting

Point

Request

00 08 6D B402 01 01 81 02

Address

Function

Code

CRC

Exception

Code

Exception Response

C1 91

Data Type Addresses Offsets Functions

Coil 0000109999 09998 01,05

Discrete Input 1000119999 09998 02

Input Register 3000139999 09998 04

Holding Register 4000149999 09998 03,06

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Binary Values Single-bit data points have a value of 1 when set and 0 whencleared. Series 3 Plus Controllers support two such data types:

Discrete inputs (usually referred to simply as discretes) can onlybe read. Most are not latched and thus indicate only the instan-taneous status of the associated condition.

Coils can also be written to in order to change the operation ofthe controller in some way.

Coils 00001 through 00010 are undefined in all Series 3 PlusControllers. Depending on the software revision, attempts to readthem will return an error (early models) or zeroes (current versions).

Numeric Values Series 3 Plus Controllers support two types of numeric data points,both of which always have 16-bit (two-byte) values:

Input Registers can only be read.

Holding Registers can also be written to in order to change the

operation of the controller in some way.

Recent software revisions ofeach controller also allow you to read(but not change) each of its input registers as a holding register, atan address calculated by adding its offset to the address of the firstundefined holding register. For example, if the last defined holdingregister is 40003, input register 30009 can also be read at address40004 + 8 = 40012.

Some registers have values that are inherently integers, which arereported as such. However, most are integer representations offloating-point numbers (analog signals, for example) that are scaled

to and reported as 12-bit values (the four most-significant bits of thehigh byte are zeroes). The register value (RV) of each such numberis a linear function of its internal value (IV), as defined by its Modbusrange (Min to Max):

The range of each such variable is listed in the Modbus interfacetable of its controllers instruction manual. Because the maximumvalue of a 12-bit number is actually 4095, the true maximums areslightly less than those listed.

For variables that range from 0.0 to 102.4 percent, internal valuesabove 100 percent (and thus Modbus values over 4000) are rarelysignificant. Most but not all distributed control systems (and otherModbus hosts) can be configured to take this scaling into account.Thus, if a bar graph is being used to display the controllers outputsignal, that graph can be scaled so it reaches full-range when theModbus value is 4000. However, not every DCS has this ability those that do not would then indicate a 97.7 percent (4000 / 4096)output when the final control element is actually 100 percent open.

RV 4096 IV Min( ) Max Min( )=

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You can make a controllers Port 3 Modbus channel compatible witheither type of host by setting its Modbus Register Scaling[MODE:DLOCK 7]. When this parameter is Off, the span of all register valuesare divided by 1.024, without changing the offset. A register variablethat otherwise ranges from 0.0 to 102.4 percent would then rangefrom 0.0 to 100.0 percent.

Functions Each request frame contains a function code that defines the actionexpected of the target controller. The meaning of the request datafields is dependent on the specified function code.

The following paragraphs describe and illustrate the functions sup-

ported by Series 3 Plus Controllers. In the examples, the contents ofthe message frames are shown as hexadecimal bytes.

Read Coil Status This function reads the status of one or more coils:

The data field of the request consists of the offset of the first coilfollowed by the number of coils to be read.

The data field of the response consists of a count of the coilbytes followed by that many bytes of coil data. The coil-databytes are packed with one bit for the status of each consecutivecoil. The least significant bit of the first coil-data byte is the sta-

tus of the first coil read. If the number of coils read is not amultiple of eight, the last data byte will be padded with zeroeson the high end.

In this example, the host requests the status of coils 00011 and00012. The controllers response indicates both coils are set (On).

Note:Modbus register scaling applies only to floating-point variables (thatis, those with decimals) reported via Port 3. It does not affect integervalues or any variable reported over Port 4.

Function 01

Address

Function

Code

CRC

Coil

Data

Byte

Count

01 01

Address

Function

Code

CRCN

umber

ofCoils

Offsetof

FirstCoil

Hi Lo

00 0A

Hi Lo

Request Frame Response Frame

00 02 9D C9 01 01 01 03 11 89

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Read Input Status This function reads one or more discrete inputs:

The data field of the request consists of the offset of the first dis-crete input followed by the number of discretes to be read.

The data field of the response consists of a count of the discretedata bytes followed by that many bytes of data. The discrete-

data bytes are packed with one bit for the status of each con-secutive discrete input. The least significant bit of the firstdiscrete-data byte conveys the status of the first discrete read. Ifthe number of discretes read is not a multiple of eight, the lastdata byte will be padded with zeroes on the high end.

In this example, the host requests the status of discrete inputs10001 and 10002. The controllers response indicates that discrete10001 is cleared (Off) and 10002 is set (On).

Read HoldingRegisters

This function reads one or more holding registers:

The data field of the request consists of the offset of the first

holding register followed by the number of registers to be read. The data field of the response consists of a count of the register-

data bytes followed by that many bytes of holding-register data.The contents of each register are returned in two consecutivedata bytes (most-significant byte first).

In this example, the host requests the value of holding register40003. The controllers response indicates it is 2047.

Function 02

Add

ress

Fun

ction

Cod

e

CRC

Inpu

t

Data

ByteCou

nt

01 02

Add

ress

Fun

ction

Cod

e

CRC

Number

ofInputs

Offsetof

FirstInput

Hi Lo

00 00

Hi Lo


00 02 F9 CB 01 02 01 02 20 49

Function 03

Address

Func

tion

Code

CRC

Byte

Count

01 03

Address

Func

tion

Code

CRCN

umberof

R

egisters

S

tarting

R

egister

Hi Lo

00 02

Hi Lo


00 01 25 CA 01 03 02 FA 34

R

egister

D

ata

Hi Lo

07 FF

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Read InputRegisters

This function reads one or more input registers:

The data field of the request consists of the offset of the firstinput register followed by the number of registers to be read.

The data field of the response consists of a count of the register-data bytes followed by that many bytes of input-register data.

The contents of each register are returned in two consecutivedata bytes (most-significant byte first).

In this example, the host requests the value of input register 30001.The controllers response indicates it is 1023.

Force Single Coil This function changes the status of one coil:

The data field of the request consists of the offset of the coil fol-lowed by its desired new status. A value of 65280 (FF00H) willset the coil, while a value of zero (0000H) will clear it. Any othernew value is illegal.

If the controller is able to force the specified coil to the

requested state, its response will be identical to the request.Otherwise, it will return an Exception Response(see page 16).

This example illustrates a successful attempt to clear coil 00011.

Function 04

Address

Function

Code

CRC

Byte

Count

01 04

Address

Function

Code

CRCN

umberof

Registers

Starting

Register

Hi Lo

00 00

Hi Lo


00 01 31 CA 01 04 02 F9 80

Register

Data

Hi Lo

03 FF

Function 05

Address

Function

Code

CRC

01 05

Address

Function

Code

CRCN

ew

Coil

State

Coil

Offset

Hi Lo

00 0A

Hi Lo


00 00 ED C8 01 05 ED C800 00

New

Coil

State

Coil

Offset

Hi Lo

00 0A

Hi Lo

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Preset SingleRegister

This function changes the value of one holding register:

The data field of the request frame consists of the relativeaddress of the holding register followed by the new value to bewritten to that register (most-significant-byte first). In the Series3 Plus Controllers, the range for register variables is 0 to 4095,which is usually scaled to represent data values in the range of0 to 102.4 percent. The new value must be in the allowablerange for that register.

If the controller is able to set that register to the requested value,its response will be identical to the request. Otherwise, it willreturn an Exception Response(see page 16).

This example illustrates a successful attempt to set holding register40003 to 3072 (0C00H).

Loopback Test This function enables the host to test the communication systemthrough various diagnostic requests. Series 3 Plus Controllerssupport only diagnostic function 00 (Return Query Data):

The data field of the request consists of the diagnostic functioncode (0000H) followed by a two-byte data value (0 to FFFFH).

The response should be identical to the request.

This example shows the response of a Series 3 Plus Controller to aLoopback Test request.

Function 06

Addres

s

Functio

n

Code

CRC

01 06

Addres

s

Functio

n

Code

CRCR

egister

Value

Register

Offset

Hi Lo

00 02

Hi Lo


0C 00 2D 0A 01 06 2D 0A0C 00

Register

Value

Register

Offset

Hi Lo

00 02

Hi Lo

Function 08

A

ddress

F

unction

C

ode

C

RCD

ata

Value

Diagnostic

Code

Hi Lo Hi Lo01 08A

ddress

F

unction

C

ode

C

RCD

ata

Value

Diagnostic

Code

Hi Lo00 00

Hi Lo


55 AA 5F 24 01 08 00 00 55 AA 5F 24

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Appendix A Configuration and TestingThis appendix describes the Modbus configuration and test proce-dures that can be executed from the Engineering Panel.

Each such key sequence begins with a data group key that selects

the function of the second key. A few of these key sequences (forexample, the Port 3 Baud Rate[MODE:D COMM 3]) are assigned tospecific data pages, in which case you might need to press the datagroup key more than once to display the letter for that data page atthe end of the first step confirming display.

Pressing the CLEAR key will terminate any of these procedures andclear the display. Otherwise, they time out and automatically clearthe display after 45 seconds of keyboard inactivity.

MODE COMM 0 This procedure sets the number (01 to 64) that identifies the control-

ler within its Port 2, 3, and 4 serial communication networks. Withthe exception of redundant controllers, this ID must be unique withineach of those networks.

Press these keys to view the current Computer ID Number:

Press CLEAR to leave it unchanged, or enter the desired ID (youmust enter both digits, even if the first is a leading zero):

where the key used to enter the new value is represented as #.

MODE:D COMM 3 These parameters define the data transmission rate (4800, 9600, or19200) and parity setting (Even, Odd, or None) for the Port 3 serialcommunication channel.

The key sequence for these parameters is the same as that for the

Port 4 Baud Rateand Port 4 Parity[MODE:D COMM 4]except thatthe third key you press is 3and the resulting display is PT3.

Computer ID Number

MODE COMM

0

Comp# ##

# #

Comp# ##

ENTER

Port 3 Baud Rate

Port 3 Parity

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MODE:D COMM 4 These parameters define the data transmission rate (4800, 9600, or19200) and parity setting (Even, Odd, or None) for the Port 4 serialcommunication channel.

Pressing CLEAR at any point in this sequence aborts this procedurewithout changing the baud rate or parity for this port.

Press these keys to view the baud rate (9600 in this example):

repeat until you see

To change this setting, press the decimal key () as many times asneeded to display the desired new value:

Press ENTER to accept the displayed rate and display the parity:

Press ENTER again to save the new baud rate without changing theparity, or press the decimal key () as many times as needed to dis-play the desired new parity:

Press ENTER to accept both changes:

Port 4 Baud Rate

Port 4 Parity

MODE MODE: D

COMM

4

PT4 9600

PT419k2

PT44800

PT49600

ENTER PT4ODD

PT4EVEN

PT4NONE

PT4 ODD

ENTER

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MODE:D LOCK 0

If redundant controllers are given the same Computer ID Number

[MODE COMM 0 ], this parameter must be disabled (Off) so onlyone of them will respond to Modbus data requests to that address. Ifthey are given different ID numbers, enabling this parameter (On)allows the Modbus host to monitor both controllers.

Press these keys to view the current status of this option:


or

Press CLEAR to leave that status unchanged, enter 0 to disable thisfeature, or enter 1 to enable it:

or

MODE:D LOCK 1 These procedures set the parameters that define the level of accessthat a host device has to the controllers Modbus data:

For full, read/write access, disable both parameters.

For read-only access, disable LOCK 1 and enable LOCK 2.

To disable all Modbus communication, enable LOCK 1 (thevalue of LOCK 2 does not matter).

The key sequence for Read and Write Inhibitis the same as that forModbus While Trackingexcept that the third key you press is 1andthe resulting display is LOC1.

The key sequence for Write Inhibit Onlyis the same as that for Mod-bus While Trackingexcept that the third key you press is 2and the

resulting display is LOC2.

Modbus While Tracking

MODE MODE: D

LOCK

0

LOC0 OFF

LOC0 ON

0

LOC0 OFF

1

LOC0 ON

ENTER

Read and Write Inhibit

MODE:D LOCK 2

Write Inhibit Only

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MODE LOCK 5 1 To enable alteration of the controllers configuration and tuningparameters from the Engineering Panel, press the following keys:

If you make a mistake entering this sequence, the controller willbeep and display an Error!message on the confirming display.

When you finish reconfiguring your controller, enter the DisableReconfiguration[MODE LOCK 5 0]sequence to disable furtherchanges (otherwise, reconfiguration will be automatically disabledafter thirty minutes of keyboard inactivity):

MODE LOCK 5 0 To disable alteration of the controllers configuration and tuning

parameters from the Engineering Panel, press the following keys:

If you make a mistake entering this sequence, the controller willbeep and display an Error!message on the confirming display.

Enable Reconfiguration

MODE LOCK

5 1

LOC5 ON

ENTER

DisableReconfiguration

MODE LOCK

5 0

LOC5 OFF

ENTER

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MODE:D LOCK 7 This procedure sets the parameter that determines how Modbusholding register values transmitted through Port 3 are scaled. If it isOff, they are scaled to their full, maximum range. If it is On, they arescaled to a slightly smaller, rounded-off range (minimum to maxi-mum / 1.024). This provides compatibility with distributed controlsystems using either scaling convention.

Press these keys to view the current status of this option:


or

Press CLEAR to leave that status unchanged, enter 0 to disable this

feature, or enter 1 to enable it:

or

MODE TEST 3 To view a dynamic display of a specified serial ports communica-

tions activity, press the following keys:

where # is the numeric key corresponding to the port number. Thebar after the Rwill be in the high position if that port is currentlyreceiving a transmission, otherwise it will be low. Similarly, the barafter the Twill be high only when that port is transmitting. The port inthe above example is receiving but not transmitting.

You can then check for communications activity on any other port by

pressing the corresponding numeric key (for example, press 4 toview Port 4s activity):

Modbus RegisterScaling

MODE MODE: D

LOCK

7

LOC7 OFF

LOC7 ON

0

LOC7 OFF

1

LOC7 ON

ENTER

Serial Port Activity Test

MODE TEST

3 #

PT# R-T_

4

PT4 R-T_

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Index

C ChecksumException Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Message Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

CoilsBinary Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Force Single Coil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Read Coil Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Computer ID NumberID Number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Message Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Modbus While Tracking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Computer Inhibit

Computer Inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Setting Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

ConfigurationConfiguration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Enabling and Disabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

D Data AddressesException Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Data FormatPort 3 Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Port 4 Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Discrete InputsBinary Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Read Input Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

E Electrical StandardsInstallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Engineering PanelConfiguration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Exception ResponseException Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

F FunctionFunctions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Message Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Function 01Read Coil Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Function 02Read Input Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

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Function 03Read Holding Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Function 04Read Input Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Function 05

Force Single Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Function 06

Preset Single Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Function 08Loopback Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

H Holding RegistersPreset Single Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Read Holding Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

I Input Registers

Read Input Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21M Message Format

Message Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Modbus Register ScalingRegister Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Setting Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Modbus RTU ProtocolProtocol Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Modbus TCP ProtocolModbus Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

R Redundant ControllersID Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Modbus While Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

RS-232 Host PortsRS-232 Converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

RS-422/485 Host PortsInstallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

S Serial Port Activity TestDescription . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Surge SuppressionModbus Serial Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

SynchronizationSynchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

T Terminating ResistorsTerminating Resistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

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U

DS301/MSeries 3 Plus Antisurge Controller Modbus Data Sheet

Coil Bits

Discrete Inputs

Input Registers

Holding Registers

Series 3 PlusAntisurge ControllerModbus Data Sheet

Product Revision: 756-002

Address Coil Address Coil Address Coil

00001-10 Undefined(1) 00012 Manual Override 00014 0

00011 Automatic 00013 Safety On 00015-18 1000(2)

Address Discrete Address Discrete Address Discrete

10001 Automatic 10008 Reset 10017-20 DI Condition4-7

10002 Manual Override 10009 Tracking 10021 Run

10003 Safety On 10010 Limit 10022 POC Active

10004 Low Clamp 10011-13 DI Condition1-3 10023 0

10005 High Clamp 10014 Port 1 Fail 10024 0

10006 Recycle Trip 10015 Port 2 Fail 10025-29 DO State1-5

10007 Tran Fail 10016 Fallback

Address Register Range Address Register Range

30001-08 Channel # 0 to 102.4% 30016 Surge Count integer

30009 Received Flow 0 to 102.4% 30017 Param CRC integer

30010 DEViation -1.00 to 1.048 30018 Pressure Ratio 0 to 64

30011 SsDenominator 0 to 102.4% 30019 Temperature Ratio 0 to 64

30012 SsNumerator 0 to 102.4% 30020 Speed 0 to 102.4%

30013 Displayed OUT 0 to 102.4% 30021 Analog Output 2 0 to 102.4%

30014 Total b 0 to 102.4% 30022 Flow 0 to 102400

30015 Sigma 0 to 0.999 30023 Reported Flow 0 to 102.4%


40001 SLL Coefficient 0 to 102.4% 40004 PdLimit 0 to 102.4%

40002 Initial b 0 to 102.4% 40005 PsLimit 0 to 102.4%

40003 Actuator CS 0 to 102.4% 40006-28 Input Registers(3) see above

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This data sheet lists this controllers Modbus coils, discrete bits, and registers. The Series 3Plus Modbus implementation, including descriptions of data types, register scaling, andavailable functions, is described in Chapter 2 of IM300/M. Cross-references in the followingdescriptions are to the Antisurge Controller[IM301]instruction manual.

Note 1: An attempt to read coils 00001 through 00010 will return zeroes.

Note 2: Although they have coil addresses, bits 00015 through 00018 jointly constitute a read-

only, four-bit integer identifying the controller type.

Note 3: Each input register can also be read (but not changed) at an address calculated by add-ing its offset (its address minus 30001) to the address of the first undefined holding register.

Coil and Input Bit Descriptions

Automatic: This coil and discrete will be set when the controller is operating automatically andcleared when manual is selected. Setting this coil forces the controller into automatic, clear-ing it forces the controller into manual. See: Manual Operationin Chapter 2.

DI Condition: These discretes reflect the discrete input states. The offsets of the first three bitsare 10 greater than the input number (discrete 10011 is for D1), those for D4 to D7 are 13

greater (discrete 10017 is for D4). See: Discrete Inputsin Chapter 3.

DO State: These discretes indicate the intended states of the control relays each is set whenthe corresponding output is energized. The offset of each such bit is 24 greater than the out-put number (discrete 10025 is for CR1 and discrete 10029 is for CR5). Bits corresponding tofault relays reflect only the assigned functions and cannot indicate hardware faults.See: Discrete Outputsin Chapter 3.

Fallback: This discrete is set when any fallback strategy is being used, usually because arequired analog or serial input has failed. See: Fallback Strategiesin Chapter 5.

High Clamp: Either this or the Low Clampdiscrete is set whenever the actuator control signal isat one of its range limits. The High Clampcorresponds to the maximum and the Low Clampcorresponds to the minimum recycle or blow-off. See: Output Clampsin Chapter 8.

Limit: This discrete is set when the recycle or blow-off flow is being increased to restore CV2 orCV3 to an acceptable level. See: Pressure Limitingin Chapter 6.

Low Clamp: see High Clamp

Manual Override: This coil and discrete are set when the Manual Override[MODE:A MOR]parameter is On and cleared when it is Off. Setting this coil enables that parameter, clearingit disables it. Automatic surge protection is active during manual control only if these bits arecleared!See: Manual Overridein Chapter 2.

POC Active: This discrete is set when the recycle flow rate has been elevated to help restore a

Performance Controllers performance override control variable to an acceptable value.See: Performance Overridein Chapter 6.

Port 1 Fail: This discrete is set when the controller fails to receive Port 1 data it has been config-ured to expect. See: Serial Communication Errorsin Chapter 3.

Port 2 Fail: This discrete is set if the controller fails to detect expected communications on thePort 2 load-sharing network. See: Serial Communication Errorsin Chapter 3.

Recycle Trip: This discrete is set whenever the operating point is to the left of the Recycle Tripcontrol line. See: Recycle Trip Linein Chapter 6.
http://im301/IM301TC.pdfhttp://im301/IM301TC.pdfhttp://im301/AsgOper.pdfhttp://im301/AsgOper.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgOper.pdfhttp://im301/AsgOper.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgOper.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/IM301TC.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgOper.pdf

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Reset: This discrete is set whenever the controller is reset and is cleared thirty seconds later.See: CPU Reset Countin Appendix B.

Run: Provided the Stop Requests[MODE:A fB 1]is not disabled, this discrete is set when astartup is initiated and remains set as long as the compressor is running. See: OperatingStatein Chapter 9.

Safety On: This coil and discrete are set when the cumulative surge count is greater than zero,

thus indicating the Safety On response has increased the margin of safety, and is clearedwhen that count is reset. This coil can only be cleared, which resets that count and responseto zero. See: Surge Countersin Chapter 6.

Tracking: This discrete is set only when this controller is operating as a backup to another andis not affected by the output tracking feature. See: Redundant Controlin Chapter 2.

Tran Fail: This discrete is set when any analog input signal falls outside of its transmitter testinglimits. See: Transmitter Testingin Chapter 3.

Input and Holding Register Descriptions

Actuator CS: This holding register reports the actuator control signal, which is the intended

value of analog OUT1. You can only write to this register in manual mode. See: ActuatorControl Signalin Chapter 8.

Analog Output 2: This input register reports the intended value of analog OUT2. See: AnalogOutputsin Chapter 3.

Channel #: These input registers report the values of the corresponding analog input signals.Any channel configured as an Offset Zero Inputis compensated for a twenty percent offset.See: Signal Variablesin Chapter 3.

DEViation: This input register reports the deviation of the operating point from the surge controlline. See: Surge Control Linein Chapter 6.

Displayed OUT: This input register reports the value displayed by the OUT readout. It will beeither the same as or the complement of the Actuator CSholding register, depending on theRecycle Valve Direction[MODE:A REV]. See: Actuator Control Signalin Chapter 8.

Flow: This input register reports the digits of the Displayed Mass Flow calculated variable, priorto inserting the decimal point. See Displayed Flowin Chapter 4.

Initial b: This holding register reports the Initial Surge Control Bias[SPEC:A b 1], and writing toit changes the value of that parameter. See: Surge Control Linein Chapter 6.

PdLimit: This holding register reports the Maximum Discharge Pressure[COND:A SP 2], andwriting to it changes the value of that parameter. The Limitbit is set if that variable (CH2) isabove this limit. See: Pressure Limitingin Chapter 6.

PsLimit: This holding register reports the Minimum Suction Pressure[COND:A SP 3], and writ-ing to it changes the value of that parameter. The Limitbit is set if that variable (CH3) isbelow this limit. See: Pressure Limitingin Chapter 6.

Param CRC: This input register reports the 16-bit checksum for the controllers present set ofconfiguration and tuning parameters. See: Parameter Checksumin Appendix B.

Pressure Ratio: This input register reports the ratio of the discharge and suction pressures.See: Compression Ratioin Chapter 4.
http://im301/AsgTest.pdfhttp://im301/AsgTest.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgSeq.pdfhttp://im301/AsgSeq.pdfhttp://im301/AsgSeq.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgOper.pdfhttp://im301/AsgOper.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgTest.pdfhttp://im301/AsgTest.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgSeq.pdfhttp://im301/AsgSeq.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgTest.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgOut.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgIO.pdfhttp://im301/AsgTest.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgOper.pdf

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Printed in U.S.A.

COMPRESSOR CONTROLS CORPORATION

4725 121st Street, Des Moines, IA 50323, USAL Phone: (515) 270-0857 Fax: (515) 270-1331 Web: www.cccglobal.com

Received Flow: see Reported Flow.

Reported Flow: In a multisection compressor application, this input register reports the flowmeasurement (

P

o,r

/ 2 or W

2

/ 2) or series load balancing parameter (L) this controller issending to its companions and the Received Flowregister reports the reported flow of theAdjacent Section Controller

[MODE:A SS 5]. See: Reported Flowin Chapter 7.

S

s

Denominator: see S

s

Numerator.

S

s

Numerator: This and the S

s

Denominatorinput registers report the numerator (for example,K P

s

h

r

/ 2) and denominator (generally,

P

o,s

/2) of the selected fA mode, which jointlyindicate how closely the compressor is operating to its surge limit. If the controller is properlytuned, the compressor will not surge unless the numerator exceeds the denominator (that is,when S

s

> 1). See: Application Functionin Chapter 5.

Sigma: This input register reports the polytropic head exponent, provided the chosen fA Modecalculates that variable. See: Polytropic Head Exponentin Chapter 4.

SLL Coefficient: This holding register reports but cannot change the Surge Limit Line Coeffi-cient

[SPEC:A K]parameter. See: Application Functionin Chapter 5.

Speed: This input register reports the normalized rotational speed of the compressor.See: Rotational Speedin Chapter 4.

Surge Count: This input register reports the number of surges detected since the cumulativesurge count was last cleared. See: Surge Countersin Chapter 6.

Temperature Ratio: This input register reports the Temperature Ratio calculated variable. SeeTemperature Ratioin Chapter 4.

Total b: This input register reports the total margin of safety between the surge limit and surgecontrol lines, obtained by summing the Initial Surge Control Bias

, the derivative response,and the accumulated Safety On response. See: Surge Control Linein Chapter 6.
http://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgMNC.pdfhttp://im301/AsgMNC.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgParam.pdfhttp://im301/AsgMNC.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgPrxSg.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgCtrl.pdfhttp://im301/AsgPVs.pdfhttp://im301/AsgParam.pdf

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U

DS302/MSeries 3 Plus Performance Controller Modbus Data Sheet

Coil Bits

Discrete Inputs

Input Registers

Holding Registers

Series 3 PlusPerformance Controller

Modbus Data Sheet



00001-10 Undefined

(1)

00012 Remote 00014 0

00011 Automatic 00013 0 00015-18 1001

(2)


10001 Automatic 10009 Tracking 10022 Started

10002 Remote 10010 CH5 Selected 10023 Startup Done

10003 Low Clamp 10011-13 DI Condition1-3 10024 CV Open

10004 High Clamp 10014 Port 1 Fail 10025-29 DO State1-5

10005 Limit 10015 Port 2 Fail 10030 Speed Tracking

10006 Loaded Primary 10016 Fallback 10031 Alternate Control

10007 Tran Fail 10017-20 DI Condition4-7

10008 Reset 10021 Loaded Secondary


30001-08 Channel # 0 to 102.4% 30014 Flow 0 to 102400

30009 Displayed PV 0 to 102.4% 30015 Efficiency 0 to 10.24

30010 Displayed SP 0 to 102.4% 30016

Power 0 to 102400

30011 Displayed OUT 0 to 102.4% 30017

UsrQ 0 to 102400

30012 Param CRC integer 30018

MaxQ 0 to 102400

30013 Analog Output 2 0 to 102.4%


40001 Capacity SP 0 to 102.4% 40004 Limiting SP3 0 to 102.4%

40002 Limiting SP2 0 to 102.4% 40005-22 Input Registers (3) see above

40003 Actuator CS 0 to 102.4%

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This data sheet lists this controllers Modbus coils, discrete bits, and registers. The Series 3Plus Modbus implementation, including descriptions of data types, register scaling, andavailable functions, is described in Chapter 2 of IM300/M. Cross-references in the followingdescriptions are to the Performance Controller[IM302]instruction manual.

Note 1: An attempt to read coils 00001 through 00010 would return zeroes.

Note 2: Although they have coil addresses, bits 00015 through 00018 jointly constitute a read-

only, four-bit integer identifying the controller type.

Note 3: Each input register can also be read (but not changed) at an address calculated by add-ing its offset (its address minus 30001) to the address of the first undefined holding register.

Coil and Input Bit Descriptions

Alternate Control: This discrete is set when the controller is regulating the fallback control vari-able (FCV) instead of CV1. See: Alternate Controlin Chapter 2.

Automatic: This coil and discrete are set when the controller is operating automatically andcleared when manual is selected. Setting this coil forces the controller into automatic, clear-ing it forces the controller into manual. See: Manual Operationin Chapter 2.

CH5 Selected: This discrete is set when the capacity control loop is applied to the CV1 AnalogInputs redundant input (CH5). See: Single Input Controlin Chapter 4.

CV Open: This discrete is set when the check valve is open. See: Check Valvein Chapter 9.

DI Condition: These discretes reflect the discrete input states. The offsets of the first three bitsare 10 greater than the input number (discrete 10011 is for D1), while those for D4 to D7 are13 greater (discrete 10017 is for D4). See: Discrete Inputsin Chapter 3.

DO State: These discretes indicate the intended states of the control relays each is set whenthe corresponding output is energized. The offset of each such bit is 24 greater than the out-put number (discrete 10025 is for CR1 and discrete 10029 is for CR5). Those corresponding

to fault relays reflect only the assigned functions and cannot indicate hardware faults.See: Discrete Outputsin Chapter 3.

Fallback: This discrete is set when any fallback strategy is being used, usually because arequired analog or serial input has failed. See: Fallback Strategiesin Chapter 4.

High Clamp: Either this or the Low Clampdiscrete is set whenever the intended flow rate is atone of its range limits. The High Clampcorresponds to the maximum and the Low Clampcorresponds to the minimum throughput. See: Output Clampsin Chapter 8.

Limit: This discrete is set when the compressor throughput is being limited to restore CV2 orCV3 to an acceptable level. See: Limiting Controlin Chapter 5.

Loaded Primary: see Loaded Secondary.Loaded Secondary: This discrete is set when a Load-Sharing Controller cannot raise the flow

through its own compressor. In contrast, the Loaded Primarydiscrete is set by a StationController that has suspended its integral control response because it cannot raise thecompressor networks total flow. See: Load Limit Conditionin Chapter 7.

Low Clamp: see High Clamp

Port 1 Fail: This discrete is set when the controller fails to receive Port 1 data it has been config-ured to expect. See: Serial Communication Errorsin Chapter 3.
http://im302/IM302TC.pdfhttp://im302/IM302TC.pdfhttp://im302/PrfOper.pdfhttp://im302/PrfOper.pdfhttp://im302/PrfOper.pdfhttp://im302/PrfOper.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfOper.pdfhttp://im302/IM302TC.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfOper.pdf

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Port 2 Fail: This discrete is set if the controller fails to detect expected communications on thePort 2 load-sharing network. See: Serial Communication Errorsin Chapter 3.

Remote: This coil and discrete are set when the remote set point is selected and cleared whenthe local set point is. If both of them are enabled, setting this coil selects the remote setpoint, clearing it selects the local set point. See: CV1 Set Pointin Chapter 5.

Reset: This discrete is set whenever the controller is reset and is cleared thirty seconds later.

See: CPU Reset Countin Appendix B.

Speed Tracking: This discrete is set when the output signal is being held equal to a rotationalspeed reported by a companion speed controller or set by another device via the speed/out-put tracking analog input. See: Speed or Output Trackingin Chapter 2.

Started: This discrete is set at the beginning of the loading sequence, while the Startup Donediscrete is set at the end of that sequence. Both are cleared at the beginning of the idlesequence. See: Automatic Sequencesin Chapter 9).

Startup Done: see Started

Tracking: This discrete is set only when this controller is operating as a backup to another and

is not affected by the speed tracking feature. See: Redundant Trackingin Chapter 9.Tran Fail: This discrete is set when any analog input signal falls outside of its transmitter testing

limits. See: Transmitter Testingin Chapter 3.

Holding and Input Register Descriptions

Actuator CS: This holding register reports the actuator control signal, which is usually theintended value of analog OUT1. You can only write to this register in manual mode.See: Actuator Control Signalin Chapter 8.

Analog Output 2: This input register reports the intended value of analog OUT2. See: AnalogOutputsin Chapter 3.

Capacity SP: This holding register reports and can change the specified Computer Remote SetPoint[MODE:D LOCK 8]. If LOCK 8 is On, this holding register provides exclusive read-and-write access to the remote set points target value. If LOCK 8 is Off, it provides read-and-write access to the local set point target (which the operator can still change using the Raiseand Lower keys. Writing to this register will not affect the control action unless or until thespecified set point is selected, which can be done by forcing the Remotecoil. If LOCK 8 isOn and Application Function[MODE:P fA]03 is selected, this register is unused and itsvalue is meaningless. See: CV1 Set Pointin Chapter 5.

Channel #: These input registers report the values of the corresponding analog input signals.Any channel configured as an Offset Zero Inputis compensated for a twenty percent offset.

See: Signal Variablesin Chapter 3.Displayed OUT: This input register reports the value displayed by the OUT readout. It will be

either the same as or the complement of the Actuator CSholding register, depending on theDisplay Output Reverse[MODE:P fD 1]setting. See: Actuator Control Signalin Chapter 8.

Displayed PV: This input register reports the value of the capacity control variable.See: Capacity Control Variablein Chapter 4.

Displayed SP: This input register reports the target value of the selected capacity control setpoint. See: CV1 Set Pointin Chapter 5.
http://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfTest.pdfhttp://im302/PrfTest.pdfhttp://im302/PrfOper.pdfhttp://im302/PrfOper.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfOper.pdfhttp://im302/PrfCVs.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfOut.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfIO.pdfhttp://im302/PrfSeq.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfTest.pdfhttp://im302/PrfIO.pdf

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Printed in U.S.A.

COMPRESSOR CONTROLS CORPORATION

4725 121st Street, Des Moines, IA 50323, USAL Phone: (515) 270-0857 Fax: (515) 270-1331 Web: www.cccglobal.com

Efficiency: This input register reports the digits of a Station Controllers system efficiency(inverse specific power consumption) variable. See System Efficiencyin Chapter 7.

Flow: This input register reports the digits of a Station Controllers measured total flow variable,prior to applying the Flow Variables Decimal

. See: Measured Total Flowin Chapter 7.

Limiting SP2: This holding register reports the CV2 Control Threshold

[COND:P SP 2], and writ-ing to it changes the value of that parameter. The Limitbit is set if that variable is beyond this

limit. See: Limiting Controlin Chapter 5.

Limiting SP3: This holding register reports the CV3 Control Threshold

[COND:P SP 3], and writ-ing to it changes the value of that parameter. The Limitbit is set if that variable is beyond thislimit. See: Limiting Controlin Chapter 5.

Param CRC: This input register reports the 16-bit checksum for the controllers present set ofconfiguration and tuning parameters. See: Parameter Checksumin Appendix B.

MaxQ: This input register reports the digits of a Station Controllers available flow variable,prior to applying the Flow Variables Decimal

. See: Available Flowin Chapter 7.

Power: This input register reports a Station Controllers total drive power variable. See: Total

Drive Powerin Chapter 7.

UsrQ: This input register reports the digits of a Station Controllers summed total flow variable,prior to applying the Flow Variables Decimal

. See: Summed Total Flowin Chapter 7.
http://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfTest.pdfhttp://im302/PrfTest.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfLdSh.pdfhttp://im302/PrfTest.pdfhttp://im302/PrfCtrl.pdfhttp://im302/PrfParam.pdfhttp://im302/PrfParam.pdf

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U

DS303/MSeries 3 Plus Dual-Loop A/P Controller Modbus Data Sheet

Coil Bits

Discrete Inputs

Input Registers

Holding Registers

Series 3 PlusDual-Loop A/P Controller

Modbus Data Sheet



00001-10 Undefined

(1)

00012 Auto Performance 00014 0

00011 Auto Antisurge 00013 Safety On 00015-18 1110

(2)


10001 Auto Antisurge 10009 ESD Request 10023 Port 2 Fail

10002 Auto Performance 10010 Stop Request 10024 Tracking

10003 Safety On 10011 Run Request 10025-29 DO State

10004 Recycle Trip 10012 Started 10030 Load Limit

10005 CLV Limit 10013 Startup Done 10031 CV Open

10006 Loaded Secondary 10014-20 DI Condition 10032 POC Active

10007 Tran Fail 10021 Fallback

10008 Reset 10022 Port 1 Fail


30001-08 Channel # 0 to 102.4% 30017 Param CRC integer

30009 DEViation -1.00 to 1.048 30018 Pressure Ratio 0 to 16

30010 Antisurge OUT 0 to 102.4% 30019 Speed 0 to 102.4%

30011 Performance OUT 0 to 102.4% 30020 Flow 0 to 102400

30012 Received Flow 0 to 102.4% 30021 MaxQ 0 to 102400

30013 Total b 0 to 102.4% 30022 UsrQ 0 to 102400

30014 S

s

Denominator 0 to 102.4% 30023 Efficiency 0 to 10.24

30015 S

s

Numerator 0 to 102.4% 30024 Reported Flow 0 to 102.4%

30016 Surge Count integer


40001 CCV Set Point 0 to 102.4% 40005 RLV Threshold 0 to 102.4%

40002 Antisurge CS 0 to 102.4% 40006 Displayed PV 0 to 102.4%

40003 Performance CS 0 to 102.4% 40007-30 Input Registers

(3)

see above

40004 CLV Threshold 0 to 102.4%

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May 2009 Page 2 of 4 DS303/M (6.1.1)

This data sheet lists this controllers Modbus coils, discrete bits, and registers. The Series 3Plus Modbus implementation, including descriptions of da

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IM300M