Siemens SIRIUS 3RW5 series - Function Code 23 (Read;Write Multiple Registers)

Messages and diagnostics
7.2 Function Codes
SIRIUS 3RW5 Modbus TCP communication module
Manual, 03/2018, A5E43676481002A/RS-AA/001
59
7.2.7
Function Code 23 (Read/Write Multiple Registers)
This function enables the Modbus client system to write and read several registers from
3RW5 register memory area using a single function call.
Note
Read/Write Multiple Registers
With the FC
23, it is only possible to access the process image output (PIQ) and the process
image input (PII).
The write operation is the first executed operation here. This function is the typically used
function call for outputting cyclic data in the 3RW5 soft starter and for reading back inputs or
device statuses.
A valid address from the bit memory area is expected as the start address. The selected
address must be designated as writable in the data tables in chapter Data tables (Page 75).
Request telegram
Address Field
Function Code
Start address read
operation
Number of registers
(read access)
7 bytes
1 byte
2 bytes
2 bytes
-
0x17
0x8000
0x0008
Start address write
operation
Number of registers N
(write access)
Number of bytes
(write access)
Data (write access)
2 bytes
2 bytes
1 byte
N x 2 bytes
0x8200
0x0001
0x01
0x0041
Response telegram
Address Field
Function Code
Number of bytes N
Data
7 bytes
1 byte
1 byte
N x 2 bytes
-
0x17
0x0010
-