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MODBUS RTU Quad2000 communication protocol

Supported device types and versions
Communication line configuration
Communication station configuration
I/O tag configuration
Changes and modifications
Document revisions

Supported device types and versions

MODBUS RTU supports the communication with the control systems Quad 2000 of Cooper turbo-compressors.

Communication line configuration

Communication station configuration

  • Communication protocol: MODBUS RTU Quad2000.
  • Address is MODBUS address that is set in Quad 2000.

Station protocol parameters

Configuration dialog box - tab "Protocol parameters".
They influence some optional parameters of protocol. You can define the following parameters:

Table 1

Key wordFull nameDescriptionUnitDefault value
Retry CountNumber of retry calls when an error in communication occurs.-2
Retry TimeoutDelay between retry calls if an error in communication occurs.ms100 millisec.
Wait First TimeoutFirst waiting on the response after sending a call.ms100 millisec.
Wait TimeoutDelay between the readings of a response until it is completed.ms100 millisec.
Max Wait RetryNumber of retry response reading until it is completed.-20

String with protocol parameters is written according to this rule:

Key_word=value;Key_word=value; ...



If a key word with valid value has not been found in the initial string, default value is used according to Table 1.

I/O tag configuration

I/O tags: Ai, Ao, Ci, Co, Di, Do

For relation between D2000 Value Type and Modbus Data Type Pre is applied this table:

Modbus Data TypeD2000 Value Type
Coil Status - 0x referencesDo
Input Status - 1x referencesDi
Input Registers - 3x referencesAi, Ci
Holding Registers - 4x referencesAo, Co

The address is Modbus register number in the range of 0 to 65535.

For Ai and Ci points, you must define a type of conversion to physical units. Conversion type RTD, 0-10V, 4-20mA, 1-5V or none is specified in Literature. You can get more detail information about settings of channels directly browsing the channel configuration on Quad display. You can also get the limit values "Zero" and "Range" for the conversion of voltage or current inputs.


  • COOPER TURBOCOMPRESSOR - Centrifugal Compressor Quad 2000 - Modbus Communication Description - Release EDR-K-041 Rev.1

Changes and modifications


Document revisions

  • Ver. 1.0 - October 29, 2002 - Creation of document
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