/
MODBUS Damatic RTU

MODBUS Damatic RTU

Valmet Damatic MODBUS RTU communication protocol

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

-

Changes and modifications

-

Document revisions

  • Ver. 1.0 – February 9, 2000

Related pages:

Communication protocols