10-04-2017, 08:12 PM
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Presented by:
Almustafa Mohamed Basi
The PLC Cycle
-The PLC is initialized internally when the power is turned on
-If no error are detected, the overseeing processes , program execution, I/O refreshing, and peripheral device servicing are executed consecutively (cyclically)
-The average cycle time can be monitor from a Peripheral Device
Self-diagnosis Functions
-The PLC is equipped with a variety of self-diagnosis function to help identify and correct errors that might occur and reduce down time
-PLC errors are divided into 2 categories based on the severity of the errors
1.Fatal errors are more serious errors which stop PLC operation
2.Non-fatal errors are less serious and don t stop PLC operation