Valmet Damatic MODBUS RTU communication protocol

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

Supported device types and versions


MODBUS protocol, version RTU, supports data reading from a Valmet Damatic control system by means of RTU GTW:LIS gateway.

Communication line configuration


  • Communication line category: Serial.
  • Parameters of the asynchronous line depending on the design and type of device connection – see the documentation "Overview of the Damatic XD System – VALMET Automation V.5.4 rev.7".

Communication station configuration


  • Communication protocol: Valmet MODBUS RTU GTW:LIS.
  • The station address is a decimal number in the range of 0 to 255.


Station protocol parameters

There can be defined the following parameters:

Table 1

KeywordFull nameMeaningUnitDefault value
RC
Retry CountThe number of request retries when an error in communication occurs.-2
RT
Retry TimeoutThe delay between request retries if an error in communication occurs.ms300 millisec.
WFT
Wait First TimeoutFirst waiting for a response after sending a request.ms200 millisec.
WT
Wait TimeoutDelay between the readings of a response until it is completed.ms100 millisec.
MWR
Max Wait RetryThe number of reading the response until it is completed.-10

String with protocol parameters is written according to this rule:

Key_word=value;Key_word=value; ...

Example:

RC=1;RT=500;

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, Di

Address – a decimal number in the range of 0 to 65535 – number of MODBUS register.

In general, 2 bytes are read (signed integer) from a particular register. For Ai points, IEE 754 standard can be used, which means a reading of 4 bytes in format FLOAT, i.e. the registers with addresses Address and Address+1.

For Di points, the bit number must be specified, withing range 0 to 15 – it represents one bit from a 16-bit MODBUS register which was read.

Literature


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Changes and modifications


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Document revisions


  • Ver. 1.0 – February 9, 2000

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