Siemens 6RA8018-6DV62

Descriptions of functions
10.8 Communication via Modbus TCP
SINAMICS DCM DC Converter
Operating Instructions, 12/2018, A5E34763375A
547
10.8.5.2
Examples: Read parameter
Table 10- 56 Write parameter request: Reading parameter value of r0002 from device number 17
Value
Byte
Description
MBAP header
10 h
0258 h
0007 h
0E h
7
8,9
10,11
12
Function code (write multiple)
Register start address
Number of registers to be read (40601 … 40607)
Number of data bytes (7 registers, each 2 bytes = 14 bytes)
0001 h
2F0A h
8001 h
0101 h
1001 h
0002 h
0000 h
13,14
15,16
17,18
19,20
21,22
23,24
25,26
40601: DS47 Control = 1 (activate request)
40602: Function 2F h (47), request length 10 bytes (0A h)
40603: Request reference = 80 h, request identifier = 1 h
40604: DO-Id = 1, number of parameters = 1
40605: Attribute, number of elements = 1
40606: Parameter number = 2
40607: Subindex = 0
Table 10- 57 Start parameter request: Reading parameter value of r0002 from device number 17
Value
Byte
Description
MBAP header
03 h
0258 h
0007 h
0010 h
7
8,9
10,11
12,13
Function code (read)
Register start address
Number of registers to be read (40601 … 40607)
Number of registers
Table 10- 58 Response for successful read operation
Value
Byte
Description
MBAP header
03 h
20 h
7
8
Function code (read)
Number of following data bytes (20 h: 32 bytes ≙ 16 registers)
0002 h
2F08 h
8001 h
0101 h
0301 h
001F h
9,10
11,12
13,14
15,16
17,18
19,20
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)
Table 10- 59 Response for unsuccessful read operation - read request still not completed
Value
Byte
Description
MBAP header
03 h
20 h
7
8
Function code (read)
Number of following data bytes (20 h: 32 bytes ≙ 16 registers)
0001 h
2F00 h
0004 h
9,10
11,12
13,14
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)