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
| Keyword | Full name | Meaning | Unit | Default value |
|---|---|---|---|---|
RC | Retry Count | The number of request retries when an error in communication occurs. | - | 2 |
RT | Retry Timeout | The delay between request retries if an error in communication occurs. | ms | 300 millisec. |
WFT | Wait First Timeout | First waiting for a response after sending a request. | ms | 200 millisec. |
WT | Wait Timeout | Delay between the readings of a response until it is completed. | ms | 100 millisec. |
MWR | Max Wait Retry | The 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
-
Document revisions
- Ver. 1.0 – February 9, 2000
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