Siemens SINAMICS V20 Operating Instructions Manual page 186

Communicating with the PLC
7.2 MODBUS communication
Example: Set p1121 = 12.15
Write parameter request: Writing the parameter value of p1121 from slave number 17
Value
11 h 1
10 h
0258 h
000A h
14 h
0001 h
2F10 h
8002 h
0101 h
1001 h
0461 h
0000 h
0801 h
4142 h
6666 h
xx h
xx h
Start parameter request: Writing the parameter value of p1121 from slave number 17
Value
11 h 1
03 h
0258 h
0007 h
0010 h
xx h
xx h
Response for successful write operation
Value
11 h 1
03 h
20 h
0002 h
2F04 h
8002 h
0101 h
xx h
xx h
184
Byte Description
Slave address
2 Function code (write multiple)
3,4 Register start address
5,6 Number of registers to be written to (40601 ... 40610)
7 Number of data bytes (10 registers, each 2 bytes = 20
bytes)
8,9 40601: C1 (activate request)
10,11 40602: Function 2F h (47), request length 16 bytes (10 h)
12,13 40603: Request reference = 80 h, request identifier = 2 h
(write)
14,15 40604: DO-Id = 1, number of parameters = 1
16,17 40605: Attribute, number of elements = 1
18,19 40606: Parameter number = 1121
20,21 40607: Subindex = 0
22,23 40608: Format + number of values
24,25 40609: Parameter value 12,15
26,27 40610: Parameter value
28 CRC "Low"
29 CRC "High"
Byte Description
Slave address
2 Function code (read)
3,4 Register start address
5,6 Number of registers to be written to (40601 ... 40610)
7,8 Number of registers
9 CRC "Low"
10 CRC "High"
Byte Description
Slave address
Number of following data bytes (20 h: 32 bytes ≙ 16 regis-
2 Function code (read)
3
ters)
4,5 40601: DS47 Control = 2 (request was executed)
6,7 40602: Function code 2F h (47), response length 4 bytes
8,9 40603: Request reference mirrored = 80 h,
response identifier = 2 (change parameter)
10,11 40604: DO-ID = 1, number of parameters = 1
12 CRC "Low"
13 CRC "High"
SINAMICS V20 Converter
Operating Instructions, 10/2019, A5E34559884-012