What should you watch out for when creating or moving F runtime groups and using the F library "Failsafe Blocks (V1_2)" or "Failsafe Blocks (V1_1)"?
To optimize reaction times for the F program, certain blocks of the S7 F system are automatically moved into the first or last runtime group of their disabling group during compilation. If an F runtime group is placed before the first or after the last F runtime group, this might result in passivation of F I/Os or of the CPU-CPU communication during the delta load.
When should you expect this behavior?
You should expect the behavior described above in the following cases:
- If you divide or regroup disabling groups by placing/deleting the F_PSG_M block.
- If you move F runtime groups manually in front of the first or after the last F runtime group of an F disabling group.
- When copying or recreating F charts in the CFC or SIMATIC Manager because this automatically generates F runtime groups.
How can you prevent this behavior?
You can never avoid this behavior if you redistribute runtime groups by placing/deleting/moving the F_PSG_M block. In this case, the module drivers and communication blocks must be moved from one disabling group to another. (See note in the manual "Configuring and programming S7 F/FH systems" on page 140).
Otherwise you can avoid passivation by using the F library "S7 F System Lib V1_3". If you use F library "Failsafe Blocks (V1_2)" or "Failsafe Blocks (V1_1)", you can avoid the behavior as follows:
|Before inserting F charts||
|Before delta loading||
You can avoid checking the output module driver if you use S7 F systems as of V5.2 SP4.