Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

3.2 AN EXAMPLE OF A COMPUTER IN MANUFACTURING

 

· PLC's are an example of a microcomputer used for industrial control

 

· The basic components in a PLC are,

  1. - CPU
  2. - RAM to store working variables, statuses, etc.
  3. - ROM to store the operating system, and programs for interpreting ladder logic, programming, etc.
  4. - A/D, D/A - To input and output analog signals from the PLC, these I/O devices are used
  5. - PIA (Parallel Interface Adapter) - used to drive parallel data lines for digital I/O. These lines are used for detecting switch closures, driving relays for outputs, turning indicator lights on and off, etc.
  6. - ACIA (Asynchronous Communications Interface Adaptor) - used to drive RS-232 ports (or other serial ports) for interface.