9-11
Precautions
The MCU reception done flag (above-mentioned
) turns off within a maximu of 100 µs after MRCV
instruction is executed, so that it may not turn off in the next scan after the execution of the MRCV
instruction depending on PLC scan time and the timing to execute the MRCV instruction. In that case,
the received data has been copied from the MCU to the CPU, however, note that the reception done flag
X0(X2) has been left to be on even in the next scan.
For only one received data, it is recommended to execute the MRCV instruction as soon as the reception
done flag X0(X2) turned on. However, for multiplex reception, as the rise of the reception doen flag
cannot be detected, use F-type instruction to execute the MRCV instruction for every scan.
In that case, the PLC data reception done flag X1(X3) after the execution of the MRCV instruction can be
used to tell if there are any received data.
The following is the time chart if the F161 (MRCV) instruction is executed twice in one scan.
To Next Page
Loading...
