This chapter continues the discussion of input and outputs from Chapter 2 and is a brief consideration of the processing of the signals from input and output devices. The PLC input/output unit provides the interface between the PLC controller and the outside world and must therefore provide the necessary signal conditioning to get the signal to the required level and also to isolate it from possible electrical hazards such as high voltages. This chapter includes the forms of typical input/output modules and, in an installation where sensors are some distance from the PLC processing unit, their communication links to the PLC.
PLC input/output units
This chapter continues the ...