5 - 6 5 - 6
MELSEC-Q
5 FUNCTIONS
(c) Automatic communication operation flowchart
Using the set automatic communication parameters, the automatic
communication function operates according to the repeat interval timer and
response monitoring timer settings as shown below.
Slave’s response condition
For normal response
For exception response
QJ71MT91 sends a request message
to the slave.
Response monitoring timer starts.
1)
2)
3)
QJ71MT91 receives a response
message from the slave.
4)
Repeat interval timer expires.
Response monitoring timer stops.
5)
6)
Corresponding bit of Automatic
communication operation status turns
off. (0: Normal is set)
Repeat interval timer starts.
7)
8)
Response monitoring timer expires.
9) Corresponding bit of Automatic
communication operation status turns
on. (1: Error is set)
Request
message
Request
message
2)
4)
6)
2)
9)
6)
Repeat interval
timer
Response
monitoring timer
(Master function)
QJ71MT91
MODBUS /TCP
slave device
R
8)
3)
Stop
5)
Timeout
1)
7)
1)
3)
Start
7)
2)
4)
3)
Stop
5)
1)
7)
Start
Start
Start
Start
Start
Timeout
Timeout
Timeout
Error
Recovery
Response
message
Response
message
Request
message
Request
message
Response
message
Response
message
Request
message
Request
message
