Communicating with the PLC
7.2 MODBUS communication
SINAMICS V20 Converter
Operating Instructions, 10/2019, A5E34559884-012
183
Start parameter request: Reading the parameter value of r0002 from slave number 17
Value
Byte
Description
11 h 1
Slave address
03 h
0258 h
0007 h
0010 h
2
3,4
5,6
7,8
Function code (read)
Register start address
Number of registers to be read (40601 … 40607)
Number of registers
xx h
xx h
9
10
CRC "Low"
CRC "High"
Response for successful read operation
Value
Byte
Description
11 h 1
Slave address
03 h
20 h
0002 h
2F08 h
8001 h
0101 h
0301 h
001F h
2
3
4,5
6,7
8,9
10,11
12,13
14,15
Function code (read)
Number of following data bytes (20 h: 32 bytes
≙
16 regis-
ters)
40601: DS47 Control = 2 (the request was executed)
40602: Function code 2F h (47), response lengths 8 bytes
40603: Request reference mirrored = 80 h,
response identifier = 1 (request parameter)
40604: DO-ID = 1, number of parameters = 1
40605: Format, number of elements = 1
40606: Parameter value = 1F h (31)
xx h
xx h
16
17
CRC "Low"
CRC "High"
Response for unsuccessful read operation - read request still not completed
Value
Byte
Description
11 h 1
Slave address
03 h
20 h
0001 h
2F00 h
0004 h
2
3
4,5
6,7
8,9
Function code (read)
Number of following data bytes (20 h: 32 bytes
≙
16 regis-
ters)
40601: Check value 1 = request is processed
40602: Function 2F h(47), response length 0 (fault)
40603: Error code: 0004 Response Not Ready (response has
still not been issued)
xx h
xx h
10
11
CRC "Low"
CRC "High"
Summary of Contents for SINAMICS V20 Inverter
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