PLC automatic control system to improve the reliability
1. The main reasons for the lower control system reliability
Although the main reason for the decline in industrial control system reliability and control aircraft PLC itself has high reliability But if the input signal to the PLC Switch mistakes analog signal larger deviations, Output PLC control by the implementing agencies do not require action, which will enable control of mistakes The economic losses caused irreparable. PLC wrong signal to the scene affect the importation of the main reasons are: 1. Signal transmission line caused a short circuit or open circuit (due to mechanical shearing, their aging lines connecting dislocation). When the signal transmission line failure, the signal can not be transmitted to the scene PLC, the controlling mistakes. 2, the mechanical contact tremble, although close contact one scene, but that closed several PLC, Although the increase in the filter circuit hardware, software differential increased orders, but because PLC scan cycle is too short, it was possible to count, add up. Displacements orders mistake, error control results. 3, the transmitter site and switches their own fault, such as contact connections and Transmitter site reflects the normal work of non-electricity or larger deviations. These same fault control system will not function properly. Impact of implementing agencies to identify two main reasons: one, the contact is not reliable load control acti
