The watchdog is actually a timer that is used to monitor the status of the PLC scan time.
Watchdog technology is often used in electronic technology, not only PLC, but also single-chip microcomputer, etc. The role cannot be ignored.
The watchdog is actually a system monitoring timer that is used to monitor the scan time of the PLC.
We all know that the PLC program working mechanism adopts a cyclic scanning working mechanism. Each cycle requires a time, which is the scanning time.
The scanning time must be limited and cannot exceed this limit. Once it exceeds the limit, it means that there is a problem with the scanning mechanism of the PLC. The problem is generally caused by "legal and unreasonable" phenomena when the user is programming. In this case, the machine must be shut down and an alarm must be sounded. What is used to monitor it is the scanning time monitor, a system timer, commonly known as a "watchdog".
Once the watchdog is activated, the result is that the PLC will stop and alarm.
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