Siemens SIRIUS 3RW5 - Page 110

Messages and diagnostics
7.2 Function Codes
SIRIUS 3RW5 Modbus communication module
110 Equipment Manual, 03/2020, A5E43676481002A/RS-AC/003
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
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
Modbus RTU:
Slave address
Function Code
Start address read
operation
Number of registers
(read access)
1 byte
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)
CRC
2 bytes
2 bytes
1 byte
N x 2 bytes
2 bytes
0x8200
0x0001
0x01
0x0041
-