There are many reasons why a PLC might freeze. Not only hardware errors or malfunctions, but also software defects and errors can cause a PLC to freeze.
First, hardware reasons
(1) When the I/O port experiences power leakage, the machine detects an error in the I/O input/output during self-test and automatically switches to stop mode.
(2) The I/O has been burned out. When the program reaches a certain node, it needs the I/O feedback signal to continue. However, no feedback is received, so the program stops running.
(3) The circuits of the machine's extended function modules, such as the A/D module, are open or have interference.
(4) The power module is faulty.
(5) The address allocation is incorrect, or the link module is incorrect.
(6) Interference or malfunction of communication cable.
2. Software issues
(1) The program is running incorrectly and has entered an infinite loop.
(2) The system parameters were modified by the program but were not formatted.
(3) The PLC's hardware protection program starts automatically, limiting the hardware usage time.
(4) The watchdog action was triggered due to data overflow.
