plc analog input modules of software or hardware reason for the crash analysis

Programmable Logic Controller PLC runtime situation may occur crash , which caused unpredictable losses to industrial Nanda intelligent plc  production, and therefore , we must first understand the cause of the crash PLC , for reasons of investigation, software or hardware errors are likely to cause crashes PLC , the following were introduced :
1 , hardware (1) I / O channeling electrical , PLC automatically detect I / O errors , enter STOP mode. (2) I / O is damaged, the program proceeds to the needs of the I / O feedback signal , the instruction is  Nanda programmable logic control plc not executed down . ( 3 ) expansion module ( function type, such as A / D) line interference or open circuit . ( 4 ) power supply portion interference or failure. ( 5 ) PLC connection module and address allocation failed module out so ( 6 ​​) cable caused . 2 , software ( 1 ) trigger an infinite loop . ( 2 ) the program changed the contents of the system parameters area , but no initialization section. ( 3 ) protection  Nanda logic controller program starts : hardware protection , restrict the use of time ( for loan recovery ) 4 ) Data overflow step is too large, the watchdog ( can be modified DOG time ) action.