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.
  • The 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 the protocol. You can define the following parameters:

Table 1

KeywordFull nameDescriptionUnitDefault value
Retry CountThe number of request retries when an error in communication occurs.-2
Retry TimeoutThe delay between request retries if an error in communication occurs.ms100 ms
Wait First TimeoutFirst waiting for a response after sending a request.ms100 ms
Wait TimeoutDelay between the readings of a response until it is completed.ms100 ms
Max Wait RetryThe number of response readings until it is completed.-20

String with protocol parameters is written according to this rule:

Key_word=value;Key_word=value; ...



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

I/O tag configuration

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

For the relation between D2000 Value Type and Modbus Data Type, the following table applies:

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, a type of conversion to physical units must be defined. Conversion type RTD, 0-10V, 4-20mA, 1-5V, or none is specified in the documentation (see Literature). You can get more detailed information about the settings of channels directly by browsing the channel configuration on the 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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