Mitsubishi Electric MELSEC-Q Series Programming Manual page 174

■Reserved area for online change
Secure reserved area for online change by the amount to be added/changed by online change (inactive block).
• Adding/changing an SFC information device
When all SFC information devices are not set for the target block, SFC information device area will not be created in the
program file. The device area will be added to the program file when an SFC information device is added to the block by
online change (inactive block). Then, free area in reserved area for online change will be reduced. (When the target block has
already contained SFC information devices, changing the SFC information device will not reduce free area in reserved area
for online change.)
• Amount used in reserved area for online change by adding an SFC diagram symbol
The following table shows the amount used in reserved area for online change by adding an SFC diagram symbol by online
change (inactive block).
Description
Adding an SFC step in serial transition
Increasing the number branches in
selection branching
Increasing the number of branches in
parallel branching
Adding an SFC block
6 SFC PROGRAM EXECUTION
172
6.6 Operation at Program Change
Before addition After addition
(No relevant SFC blocks)
Amount used in reserved area for
online change (unit: step)
7 + Number of steps in step 2 + Number of
steps of transition condition 2
12 + Number of steps in step 5 + Number
of steps of transition condition 6 + Number
of steps of transition condition 7
7 + Number of steps in step 6
10 + Number of steps in step 0 + Number
of steps of transition condition 0 (When
SFC information device is set, further 9
steps are reduced.)