Rockwell-automation 20-COMM-I Interbus Adapter Bedienungsanleitung PDF herunterladen (Seite 72)

6-10 Using Explicit Messaging (PCP Communications)

PCP Write Message Format

PCP Writes require the following Command and Reply message

formats:

Command

Word Name Description

0CR The Communication Reference (CR #) to write to

1Index The index of the variable to write

2 Sub Index The sub-index of the variable to write (not used)

3 Data Length The # of bytes of data following (1, 2, or 4 bytes)

4 Data Word 1

Contains 8-bit (1 byte) write data (stored in the high byte),

16-bit, (2 byte) write data, and the most significant word for

32-bit (4 byte) write data

5 Data Word 2 Least significant word for 32-bit (4 byte) write data

Word Name Description

Command

Word Echo

Echo of the Command Word (0008h)

Message

Length

Number of words following

2CR The Communication Reference (CR #) the Reply is from

3 Result

Result Code:

0=Success

FFFFh = Timeout

FFFEh = Out of buffers to store the reply

FFFDh = Invalid CR

FFFCh = Could not connect to device with CR

FFFBh = Reply of Command bigger than buffer

20COMM-UM007A-EN-P.book Page 10 Tuesday, January 22, 2002 10:52 AM

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Rockwell-automation 20-COMM-I Interbus Adapter Bedienungsanleitung Seite 72