Siemens SIRIUS 3RW5 Equipment Manual page 110

Messages and diagnostics
7.2 Function Codes
7.2.7 Function Code 23 (Read/Write Multiple Registers)
This function enables the Modbus TCP client system or the Modbus RTU master system to
write and read several registers from the 3RW5 register memory area using a single function
call.
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 136).
Request telegram
Modbus TCP:
Address Field
7 bytes
-
Start address write
operation
2 bytes
0x8200
Modbus RTU:
Slave address
1 byte
-
Start address write
operation
2 bytes
0x8200
110
Function Code
1 byte
0x17
Number of
registers N (write access)
2 bytes
0x0001
Function Code
1 byte
0x17
Number of
registers N (write access)
2 bytes
0x0001
Start address read
operation
2 bytes
0x8000
Number of bytes
(write access)
1 byte
0x01
Start address read
operation
2 bytes
0x8000
Number of bytes
(write access)
1 byte
0x01
Equipment Manual, 03/2020, A5E43676481002A/RS-AC/003
Number of registers
(read access)
2 bytes
0x0008
Data (write access)
N x 2 bytes
0x0041
Number of registers
(read access)
2 bytes
0x0008
Data (write access)
N x 2 bytes
0x0041
SIRIUS 3RW5 Modbus communication module
CRC
2 bytes
-