Programmable Logic Controller (PLC) features

Industrial control equipment reliability requirements:
① MTBF long time
② time to repair (MTTR) Short
Any failure electronic devices, usually two:
① sporadic fault. Due to the harsh external environment, such as electromagnetic interference, ultra-high temperature, ultra-low temperature, over voltage, under voltage failure caused by vibration and so on. Such failures, they do not cause damage to system components, once the environmental conditions return to normal, the system also will return to normal. But for PLC, the rear outside influence, the information stored inside may be damaged.
② permanent failure. Since the components can not be restored and the destruction caused by the fault.
If we can limit the occurrence of sporadic fault condition, the consequences will not be affected if the PLC or able to make impact in harsh environments is limited to a minimum, make programmable logic controller (plc) suppliers automatically disappear after the harsh conditions return to normal, so that we can improve MTBF time; if we can increase the number of diagnostic measures and appropriate means of protection in the PLC, when a permanent failure, can quickly find the point of failure and faults locally, can reduce mean time to repair the PLC. To this end, each PLC manufacturer has taken various measures in terms of hardware and software, so that PLC in addition to their strong self-diagnostic capabilities, in time with an error message, stop waiting for repair, but also make the PLC has a very strong anti-jamming capability.