How to choose the output module plc input and output interface module type

PLC is an industrial control system, it is the object of industrial production control equipment or industrial processes , industrial work environment field . Its links with the industrial production process  digital output plc is through I / O interface module to achieve.Through the I / O interface module can detect various parameters controlled production process , and these field data as control information on the controlled object . While the I / O interface module of the processing result to the controller or industrial processes controlled device , thereby driving the various actuators to achieve control. PLC information collected from the scene and outputs a control signal to external devices are required to go through a certain distance , in order to ensure that the information is correct , PLC 's I / O interface module has better anti-interference ability . According to actual needs , under cpu modules  normal circumstances , PLC has a number of I / O interface modules , including digital input module , digital output modules , analog input module , analog output modules as well as some other special modules should be used according to their selected features .