Rockwell Automation 1395 ControlNet Communication Board - Manual (Page 38)

3–24 Configuration & PLC Interfacing
Publication 1395–5.37– March, 1999
The PMW length is determined by adding the message header length
(4 words) to the number of words required to specify the parameter list
and data. Parameter and data change requires two words in the PMW
instruction. Below is an example:
Example 1:
The PLC Controller is to read 1 parameter value from the Drive.
Message Header
PMW PMR Word 3
Message Header 4 4
8 bytes
Parameter Data 1 2 2 bytes
Total 5 words 6 words
10 bytes
The PMR message is structured the same as the PMW instruction with
the exception that the Drive will provide a status word for the
parameter. If the parameter value is accepted by the Drive, the status
byte in word four will indicate that the message was successful. If the
message status indicates an error, then the PLC Controller program
must check the parameter status word to determine which parameter(s)
was not accepted by the Drive.