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The watchdog module monitors system parameters including: • the application loop maximum execution time in order to detect if the process is executing its program correctly and is not looping (hang-up). • the application loop minimum execution time in order to detect if the processor is executing its program correctly and is not skipping program parts. • 5 Vdc voltage monitoring for overvoltage and undervoltage (5 Vdc ± 5 %). • memory error logic from CPU, COM and MEM modules. In case of a memory error, the watchdog output is de-energized. • ESD input to de-energize the watchdog output independently from the processor. This ESD input is 24 Vdc and galvanically isolated from the internal 5 Vdc. In order to be able to test the WD module for all functions, the WD module itself is a 2-out-of-3-voting system. Each section monitors the parameters described above. The maximum WDG OUT output current is 900 mA (fuse 1A) 5 Vdc. If the number of output modules on the same 5 Vdc supply require a higher current (total of WD input currents of the output modules), then a watchdog repeater (WDR, 10302/1/1) must be used, and the load must be divided over the WD and the WDR.