CJ2 CPU Unit Software User's Manual - CIP ETI

10 CPU Unit Functions1 Synchronous SignalWhen the power supply to the PLC is turned ON, the CPU Unit generates a synchronous signaland then starts initializing the synchronous data. The CPU Units and Synchronous Units alsostart internal processing at this time.2 Synchronous Input Data Refresh (Synchronous Units to CPU Unit)The Synchronous Units sent synchronous data to the CPU Unit.3 Synchronous Interrupt TaskThe CPU Unit executed the synchronous interrupt task. (Synchronous unit operation can beused without using the synchronous interrupt task.)4 Synchronous Processing TimeThe synchronous processing time is the time required for one series of synchronous operationprocessing in one synchronous operation cycle. It is the time from when the synchronous signalis generated until execution of the synchronous interrupt task has been completed. After the synchronousprocessing time, normal processing is performed until the synchronous control cyclehas expired.The synchronous processing time must be less than the synchronous operation cycle. (The maximumand present values of the synchronous processing time can be monitored in the SynchronousOperation Status Dialog Box of the CX-Programmer.)5 Synchronous Operation CycleWhen the synchronous operation cycle time has expired, the synchronous signal is generatedagain.6 Synchronous Output Data Refresh (CPU Unit to Synchronous Units)The CPU Unit sends synchronous data to the Synchronous Units.7 The overall process is repeated from step 2.Precautions for Correct UseThe CPU Unit interrupts normal processing during the synchronous input data refresh, synchronousinterrupt task execution, and synchronous output data refresh. The normal cycle time of theCPU Unit will be extended by the time required for these processes. Be sure that the control systemwill not be adversely affected if the cycle time is extended before using synchronous unitoperation.10-82 CJ2 CPU Unit Software User’s Manual