Mitsubishi MELSEC-Q Series User Manual page 99

4
FUNCTIONS
POINT
The following precaution must be taken when a message is sent to the
MELSECNET/H module controlled by the programmable controller CPU.
When sending data to the same channel of the receiving station with ACK set,
execute the transmission after the receiving station has read out the previously
received data with the RECV instruction.
Failure to do so will cause an error. If an error is detected, retransmit the data after
a little while.
C Controller module
MELSECNET/H module
(Sending station)
User program
ret = QBF_SEND();
ret = QBF_SEND();
4.4 MELSECNET/H Module Access Function
Network module
Channel 3
Logical channel
(Channel 5)
Error
4.4.1 Message communication
1
2
CPU (Receiving
3
station)
RECV
4
5
6
7
8
4
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