Supported device types and versions
Communication line configuration
Communication station configuration
I/O tag configuration
Literature
Changes and modifications
Document revisions
MODBUS protocol, version RTU, supports data reading from a control system Valmet Damatic by means of gateway RTU GTW:LIS.
There can be defined the following parameters:
Table 1
| Key word | Full name | Meaning | Unit | Default value |
|---|---|---|---|---|
| Retry Count | Number of retry calls when an error in communication occurs. | - | 2 | |
| Retry Timeout | Delay between retry calls if an error in communication occurs. | ms | 300 millisec. | |
| Wait First Timeout | First waiting on the response after sending a call. | ms | 200 millisec. | |
| Wait Timeout | Delay between the readings of a response until it is completed. | ms | 100 millisec. | |
| 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 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.
-
-