Programmable Logic Controller (PLC): Objectives

Goals:

1. Describe the four basic parts of any programmable logic controller (PLC).

2. Explain how a PLC program is different from a BASIC or Fortran program.

3. Explain the four things that occur when the PLC processor scans its program.

4. Compare how a PLC controls a conveyor sorting system to the way a typical solid-state logic circuit would control it.

above: PLC modules by Hitachi.

5. Explain the function of an input module and describe the circuitry used to complete this function.

6. Explain the function of an output module and describe the circuitry used to complete this function.

7. Explain the function of an internal control relay.

8. Discuss the classifications of PLCs.

9. Describe what happens when a PLC is in run mode.

10. Explain the function of the address of an in- put or output to the PLC processor and to the technician who must troubleshoot the PLC.

11. Identify the input and output instructions for a PLC.

12. Explain what a mnemonic is.

13. Read and interpret a PLC program.

14. Explain the operation of a latch and unlatch coil.

15. Explain the operation of a PLC on-delay timer.

16. Explain the operation of a PLC up counter and down counter.

17. Explain how a PLC timer or counter can reach values above 9999.