Mitsubishi Electric FX5 User Manual page 149

■Precautions for sending
When sending data, please take care about the following.
• While the sending request flag is ON, do not change the amount of send data or the contents of the send data.
• Do not set the sending request flag to OFF in the program. If the send data is changed while the sending request flag
(M8122) is ON or if the sending request flag (M8122) is set to OFF in the sequence program, correct data will not be sent.
Operation during data receive
When executing the RS2 instruction, the PLC waits to receive. When the PLC receives data from the counterpart equipment
and receiving data is completed, the receiving completed flag turns ON.
Name
Receiving completed flag
When the PLC receives data, it stores the received data to (d) to ((d)+(n2)-1).
While the receiving completed flag (M8123) is ON, the PLC cannot receive new data.
■Time at which receiving is started
When the PLC receives data while it is waiting, it starts receiving data.
When receiving begins, the PLC stores the received data in interrupt processing regardless of the operation cycle.
However, when the headers are specified in the communication settings, the PLC starts receiving when it continuously
receives the codes set in the headers. The PLC stores the received data except the headers.
■Time at which receiving is completed
The time at which receiving is completed falls into the following 3 types. Receiving is completed when one of the following
conditions is satisfied.
• When the PLC receives the amount of receive data specified by the RS2 instruction
• The terminators, sum check and CR+LF configured in the communication settings are received correctly.
• • • • • • Data CR+LF
• • • • • • Data Terminator
• • • • • • Data Terminator
• • • • • • Data Terminator
• • • • • • Data Terminator
• When data receiving is suspended and the PLC does not receive the next data within the time-out time, the time-out flag
turns ON.
■Operation of time-out flag
When data receiving is suspended, and the PLC does not receive the next within the time-out time, the time-out flag is set to
ON.
At this time, the receiving completed flag is also set to ON.
The time-out time can be set within 1 to 32767 (ms). If the set value is outside the range, it operates as 10 ms.
Name
Time-out flag
time-out time
Receiving
Data
Timeout determination
SM8565
Receiving completed
SM8562
FX5 dedicated
CH1 CH2
SM8562 SM8572
CR+LF
Sum check
Sum check CR+LF
FX5 dedicated
CH1 CH2
SM8565 SM8575
SD8621 SD8631
Receive data is suspended.
Time-out time
Set to OFF in program.
SD8621×1 ms
ON
ON
CH3
SM8582
CH3 CH4
SM8585 SM8595
SD8641 SD8651
5 NON-PROTOCOL COMMUNICATION
CH4
SM8592
FX3 Series compatible
CH1 CH2
SM8409 SM8429
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5.7 Programming
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