A programming device: programmer PLC development and application, monitoring operation, inspection, maintenance, an indispensable device for programming the system set to monitor the working conditions of the PLC and the PLC control system, but it is not directly involved in site control run, small programming PLC generally hand-held programmer, generally by the computer (running programming software) to act as a programmer.
Man-machine interface: the most simple man-machine interface is the lights and buttons, LCD screen (or touch screen), one operator terminal applications are more widely used, by the computer (running the configuration software) to act as man-machine interface very popular. 3, the input and output devices: used to permanently store user data, such as EPROM, EEPROM write, the bar code reader input analog potentiometer, printers, etc.