There are many reasons that cause the PLC to crash. Software and hardware errors may cause the PLC to crash. This article will introduce the hardware and software.

1. Hardware

(1) When I/O is powered on, PLC automatically detects I/O error and enters STOP mode. 

(2) The I/O is damaged, and the program cannot execute the command downward when it runs to the feedback signal that needs the I/O.

(3) Line interference or open circuit of expansion module (functional type, such as A/D).

(4) The power part has interference or fault.

(5) The connection module and address assignment module of PLC are faulty.

(6) Faults caused by cables.

Causes of PLC crash

2. Software

(1) An endless loop was triggered.

 (2) The program overwrites the contents of the system parameter area, but there is no initialization part.

(3) Protection program start: hardware protection, limited use time (for payment recovery)

(4) Data overflow, excessive step size, watchdog (can modify the DOG time) action.