Mitsubishi MELSEC-Q Series Programming Manual page 208

6 SFC PROGRAM EXECUTION
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(9) Precautions
(a) Online change from another GX Works2
If GX Works executes online change (inactive block) while another GX
Works2 executes online change or program backup, a communication error
will occur.
The same occurs if another GX works executes online change or program
backup while GX Works2 executes online change (inactive block).
(b) Excess of the number of SFC steps
After addition of SFC steps, if the number of SFC steps exceeds the number
of step relay (S) points set in the Device tab of the PLC parameter dialog box,
a communication error will occur.
(c) Online change (inactive block) during boot operation
When online change (inactive block) is executed during boot operation from a
memory card, the original program in the memory card will not be changed.
(d) Operation if the CPU module is powered off and then on or is reset before
termination of online change (inactive block)
The changes in the target program will not be reflected.
(e) Online change (inactive block) immediately after writing to the CPU module
When the CPU module is set to STOP and an SFC program is written to the
CPU module, online change (inactive block) cannot be executed to the SFC
program until when the CPU module is set to RUN.
If executed, a communication error will occur.
(f) Online change (inactive block) while "CAN'T EXE.PRG." (error code: 2504)
occurs
When multiple SFC programs of scan execution type are registered and
"CAN'T EXE.PRG." (error code: 2504) occurs, online change (inactive block)
cannot be executed. If executed, a communication error will occur.
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