Mitsubishi Electric M800VW Series Manual page 177

M800V/M80V Series PLC Development Manual
5 Peripheral Development Environment (GX Works2)
5.6 Developing Simple Project
Precautions for command operation in ladder programming writing during RUN
(1) When commanding rising/ falling edge
When rising or falling edge is commanded in ladder program writing during RUN, the following action will be taken after
the command. The rising/falling edge may not always be executed in the first processing cycle due to the change of oper-
ation path such as subroutine call or jump junction.
Rising/falling commands in contact sys-
tem
LDP, LDF, ANDP, ..., MEP, MEF, ...
PLS, PLF, FF, MOVP, ～ P, ...
(2) When a device is deleted in the program
If an output command is deleted in the program, the output status of the device designated by the command will be kept
as before the deletion.
(3) When a program error occurs in RUN write
When a program error occurs in the process of RUN write, the display of the error step may be inaccurate regardless of
the relation of the command and the error point.
(4) Actual updating timing of program in RUN write
An updated program may not be executed in the cycle right after the RUN write (after executing the ladder conversion).
The actual execution of the updated program may be delayed by a few or a few dozens cycles, because the processing
time of RUN write depends on the total number of steps used in the sequence programs and the points where the steps
are written in.
"Ladder programming writing during RUN" operation
Main processing
executing cycle
Ladder program writing processing time
IB-1501614-B
The first execution after
change
Command status is OFF
Execute the program
before conversion
Actual program updating
152
The second execution after
change
Normal execution
Update