Read Parameter - Siemens SINAMICS G110M Function Manual

Communication via RS485
5.4 Communication using Modbus RTU
5.4.6.1

Read parameter

Example: r0002 read acyclically
Table 5- 18 Write parameter request: Reading the parameter value of r0002 from slave number 17
Byte Description
Header
11 h 0 Slave address
10 h 1 Function code (write multiple)
0258 h 2,3 Register start address
0007 h 4,5 Number of registers to be read (40601 ... 40607)
0E h 6 Number of data bytes (7 registers, each 2 bytes = 14 bytes)
User data
0001 h 7,8 40601: DS47 Control = 1 (activate request)
2F0A h 9,10 40602: Function 2F h (47), request length 10 bytes (0A h)
8001 h 11,12 40603: Request reference = 80 h, request identifier = 1 h
0101 h 13,14 40604: DO-Id = 1, number of parameters = 1
1001 h 15,16 40605: Attribute, number of elements = 1
0002 h 17,18 40606: Parameter number = 2
0000 h 19,20 40607: Subindex = 0
Table 5- 19 Start parameter request: Reading the parameter value of r0002 from slave number 17
Byte Description
11 h 0 Slave address
03 h 1 Function code (read)
0258 h 2,3 Register start address
0007 h 4,5 Number of registers to be read (40601 ... 40607)
0010 h 6,7 Number of registers
Table 5- 20 Response for successful read operation
Byte Description
Header
11 h 0 Slave address
Number of following data bytes (20 h: 32 bytes ≙ 16 registers)
03 h 1 Function code (read)
20 h 2
User data
0002 h 3,4 40601: DS47 Control = 2 (the request was executed)
2F08 h 5,6 40602: Function code 2F h (47), response lengths 8 bytes
8001 h 7,8 40603: Request reference mirrored = 80 h,
response identifier = 1 (request parameter)
0101 h 9,10 40604: DO-ID = 1, number of parameters = 1
0301 h 11,12 40605: Format, number of elements = 1
001F h 13,14 40606: Parameter value = 1F h (31)
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Function Manual, 01/2016, FW V4.7 SP6, A5E34229197B AC
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