CHAPTER 13 RS-485 COMMUNICATIONS
13-26
Modbus RTU Communications
13
Positioning data (divided)
Positioning data are 4 bytes long for each set. The positioning status, M code, and the stop timer
are configured as follows. All other items are configured in the same way as positioning data
(batch).
00h
00h
Positioning status
DATA
4bytes
M code
00h
00h
Stop timer (H)
DATA
4bytes
Stop timer (L)
5. Exceptional responses
The amplifier returns an exceptional response if it has not succeed the process specified by a query.
The message frame is as follows. This is common to all FC values.
Station No. 1 byte
FC 1 byte
Exceptional
code
1 byte
(L)
CRC check
16 bits
(2 bytes)
(H)
(1) Function code (FC) field
Exceptional responses from slaves are returned as one is set on the MSB of the FC specified by the
query.
Query Exceptional response
01h 81h
03h 83h
05h 85h
08h 88h
0Fh 8Fh
10h 90h
17h 97h
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