Rockwell Automation 1395 Multi-Comm Hardware/Software - Manual (Page 56)

Chapter 3
Configuration & Interfacing
3–45
The BTW length is determined by adding the message header length (4
words) to the number of words required to specify the parameter list and
data. Each parameter change requires two words in the BTW instruction.
Below are two examples:
Example 1:
The PLC Controller is to read 1 parameter value from the Drive.
Message Header
BTW BTR Word 3
Message Header 4 4
8 bytes
Parameter Data 1 2 2 bytes
Total 5 words 6 words
10 bytes
Example 2:
The PLC Controller is to read 3 parameter values from the Drive.
Message Header
BTW BTR Word 3
Message Header 4 4
8 bytes
Parameter Date 5 6 10 bytes
Total 9 words 10 words
18 bytes
The BTR message is structured the same as the BTW instruction with the
exception that the Drive will provide a status word for each parameter. If
all parameter values were 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 for each parameter to determine which parameter(s)
were not accepted by the Drive.