高可靠性是電氣控制設備的關鍵性能。PLC由于采用現(xiàn)代大規(guī)模集成電路技術，采用嚴格的生產(chǎn)工藝制造，內(nèi)部電路采取了 的抗干擾技術，具有很高的可靠性。使用PLC構成控制系統(tǒng)，和同等規(guī)模的繼電接觸器系統(tǒng)相比，電氣接線及開關接點已減少到數(shù)百甚至數(shù)千分之一，故障也就大大降低。此外，PLC帶有硬件故障自我檢測功能，出現(xiàn)故障時可及時發(fā)出警報信息。在應用軟件中，應用者還可以編入外圍器件的故障自診斷程序，使系統(tǒng)中除PLC以外的電路及設備也獲得故障自診斷保護。這樣，整個系統(tǒng)將極高的可靠性。

High reliability is the key performance of electrical control equipment. PLC adopts modern large-scale integrated circuit technology and strict production process. Its internal circuit adopts anti-interference technology, which has high reliability. Using PLC to form the control system, compared with the relay contactor system of the same scale, the electrical wiring and switch contacts have been reduced to hundreds or even thousands of times, and the fault has been greatly reduced. In addition, PLC has the function of hardware fault self-detection, which can send out alarm information in time when there is a fault. In the application software, the user can also program the fault self diagnosis program of peripheral devices, so that the circuits and equipment other than PLC in the system can also obtain fault self diagnosis protection. In this way, the whole system will be highly reliable.