Technical data

Fieldbus Communication • 227
MODBUS Functions
WAGO-I/O-SYSTEM 750
BACnet/IP Controller
4.3.3.10 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 Field name Example
Byte 0, 1 Transaction identifier 0x0000
Byte 2, 3 protocol identifier 0x0000
Byte 4, 5 length field 0x0002
Byte 6 Unit identifier 0x01 not used
Byte 7 MODBUS function code 0x16
Byte 8-9 Reference Number 0x0000
Byte 10-11 AND-Mask 0x0000
Byte 12-13 OR-Mask 0xAAAA
Response
Byte Field name Example
.....
Byte 7 MODBUS function code 0x10
Byte 8-9 Reference Number 0x0000
Byte 10-11 AND-Mask 0x0000
Byte 12-13 OR-Mask 0xAAAA
Exception
Byte Field name Example
.....
Byte 7 MODBUS function code 0x85
Byte 8 Exception code 0x01 or 0x02