Function Code Fc11 (Get Comm Event Counter) - WAGO 750 Series Manual

106 • Fieldbus Communication
MODBUS Functions

4.2.3.8 Function Code FC11 (Get comm event counter)

This function returns a status word and an event counter from the slave
device's communication event counter. By reading the current count before
and after a series of messages, a master can determine whether the messages
were handled normally by the slave.
Following each successful new processing, the counter counts up. This
counting process is not performed in the case of exception replies, poll
commands or counter inquiries.
Request
Byte
Byte 0, 1
Byte 2, 3
Byte 4, 5
Byte 6
Byte 7
Response
The reply contains a 2-byte status word and a 2-byte event counter. The status
word only contains zeroes.
Byte
.....
Byte 7
Byte 8, 9
Byte 10, 11
The event counter shows that 3 (0x0003) events were counted.
Exception
Byte
.....
Byte 7
Byte 8
Field name
Transaction identifier
protocol identifier
length field
unit identifier
MODBUS function code
Field name
MODBUS function code
Status
Event Count
Field name
MODBUS function code
Exception code
Example
0x0000
0x0000
0x0002
0x01 not used
0x0B
Example
0x0B
0x0000
0x0003
Example
0x85
0x01 or 0x02
WAGO-I/O-SYSTEM 750
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