Mitsubishi Electric MELSEC Q Series Quick Start Manual page 45

 Changing running programs <Online program change>
This function writes only the modified ladder block to the CPU module while the CPU module is in the
"RUN" status.
A program can be written in a short time since this function does not transfer the whole program.
The following is an example of adding a contact to the ladder.
Operating procedure
When the online program change has been properly completed, the following message is displayed.
Caution
The program in the CPU module and the program to be modified in GX Developer must be
the same to perform the online program change. When you are not sure, verify the
programs in advance or modify the ladder after performing the "Read from PLC" function.
1 Select ( Write mode) while
displaying the ladder.
2 Add a contact.
The ladder block is
displayed in gray.
3 Select [Convert]
[Convert (Online change)]
( key + key).
4 Click the button.
5 Click the button to
close the screen.
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