WAGO 750-341 Manual page 147

6.3.10 Function Code FC22 (Mask Write Register)
This function manipulates individual bits within a register using a combination
of an AND mask, an OR mask, and the register's current content.
Request
Byte
Byte 0, 1
Byte 2, 3
Byte 4, 5
Byte 6
Byte 7
Byte 8-9
Byte 10-11
Byte 12-13
Response
Byte
.....
Byte 7
Byte 8-9
Byte 10-11
Byte 12-13
Exception
Byte
.....
Byte 7
Byte 8
WAGO-I/O-SYSTEM 750
ETHERNET TCP/IP
Description of the MODBUS Functions
Field name
Transaction identifier
protocol identifier
length field
Unit identifier
MODBUS function code
Reference Number
AND-Mask
OR-Mask
Field name
MODBUS function code
Reference Number
AND-Mask
OR-Mask
Field name
MODBUS function code
Exception code
MODBUS Functions
Example
0x0000
0x0000
0x0002
0x01 not used
0x16
0x0000
0x0000
0xAAAA
Example
0x10
0x0000
0x0000
0xAAAA
Example
0x85
0x01 or 0x02
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