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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 control system Valmet Damatic by means of gateway RTU GTW:LIS.

Communication line configuration


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

Communication station configuration


  • Communication protocol: Valmet MODBUS RTU GTW:LIS.
  • 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

Key word Full name Meaning Unit Default value
RC Retry Count Number of retry calls when an error in communication occurs. - 2
RT Retry Timeout Delay between retry calls if an error in communication occurs. ms 300 millisec.
WFT Wait First Timeout First waiting on the response after sending a call. ms 200 millisec.
WT Wait Timeout Delay between the readings of a response until it is completed. ms 100 millisec.
MWR Max Wait Retry Number of retry response reading 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 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, Di

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

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

For Di points, number of bit must be from the range of 0 to 15 – one bit from 16 bits from 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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