Hi,

Blocks from the PCS7 libraries run in OB3x which are cyclic interrupt OB's. They run for instance each 100, 500, 1000ms depending which OB a block is inserted to.

Whenever there is a programming error (some sort of loop) or the amount of blocks in the OB is too large, the cyclic interrupt time cannot be maintained. In this case the CPU goes to emergency state where it tries to reduce the OB time by half. So a 500ms OB takes 1s to process. A stop of the CPU can be prevented. 

When the error is gone, the CPU returns to normal.state. This is the basic procedure. The CPU_RT block can be used to diagnose the problems. 

To address this issue, consider the following steps:

1. Analyze CPU Load and Cycle Times:

   • Utilize the CPU_RT function block to monitor the execution times of individual OBs and assess their contribution to the overall cycle time. This block helps in identifying tasks that may be causing CPU overload.
     Siemens Industry

2. Optimize Program Structure:

   • Review your program to ensure that time-critical tasks are assigned appropriate priorities and are executed within their designated time frames.
   • Distribute tasks across different cyclic OBs based on their required execution intervals to balance the CPU load effectively.

3. Adjust CPU Parameters:

   • Configure the CPU's cycle and response times to accommodate the processing demands of your program. Ensure that the watchdog timer settings are appropriate to prevent unintended CPU restarts due to cycle time violations.
     Siemens Industry