Following the conversion from a PL7 project in ST language to a Modicon M340 application, the behavior of converted SFBs must be checked.
Notification about Differences
The conversion of ST language including SFBs is done with a conversion error message to log all the calls of SFBs.
This is done to inform the programmer about differences that may happen, depending on the program itself.
PL7 versus Control Expert
SFBs in PL7 are managed by the PLC operating system asynchronously with the program.
On the opposite, the converted SFBs are function blocks in Control Expert, that are managed synchronously with the execution of the program.
As a consequence:
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It is mandatory to execute the function block in Control Expert at each scan time to refresh the current values (elapsed time, output). This is not mandatory in PL7.
In case of conditional calls of SFBs, take care to keep a call active as long as the SFB is running or add an unconditional call.
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Check the correct behavior of the SFBs in all operating modes of the PLC (cold start, warm start, PLC initialization, PLC running).
NOTE: A PL7_DRUM is converted in Modicon M340 applications to an empty DFB.
