This course studies various types of discrete I/O modules and devices used in PLC machine and process control. The selection and operation of discrete AC, DC, TTL, sink, source and other “specialty” modules are explained. Emphasis is placed on the construction, testing and troubleshooting of I/O circuits using a voltage tester and personal computer. Safety considerations when working with I/O circuits are also covered.

Topics include discrete AC, DC, isolated, source, sink, TTL, and

fast response input modules, AC, DC, contact and TTL output modules, module density, image tables, wiring diagrams, electrical ratings, interposing relays, leakage current and output overload protection.