The reliability of PLC is very high, and it has perfect self diagnosis function. If there is a fault, with the help of self diagnosis program, it can easily find the fault parts, and then it can return to normal work after replacement.
1. Timeout detection
The alarm set (ANS) and alarm reset (ANR) commands of Mitsubishi FX series PLC can be used to realize the function of timeout detection conveniently.
2. Logic error detection
In the normal operation of the system, there is a certain relationship between the input and output signals of PLC and the internal signals (such as the status of memory bits). If there is an abnormal logic signal, it means that there is a fault.