(ans. c)


1. Write the mnemonic program for the Ladder Logic below.



(ans. XIC 100, XIC 101, OR, OTE 201)


2. A PLC can be used effectively to,

a) replace a few relays.

b) replace customized electronics.

c) replace a highly skilled human operator.

d) control a well understood process.


(ans. d)


5. Why would relays be used in place of PLCs?


(ans. for simple designs)


6. Give an example of where a PLC could be used.


(ans. to control a conveyor system)


7. Give a concise description of a PLC.


8. List the advantages of a PLC over relays.


9. Explain the trade-offs between relays and PLCs for control applications.


10. In the figure below, if a limit switch is NO, the power the power flow to the output will normally be___________________.



(ans. off)


11. In the figure above, if a limit switch input is NC, the power indicator in the input module should be __________________.


(ans. on)


12. TRUE or FALSE - The left-most side of the PLC’s ladder diagram simulates the power line.


(ans. true)


13. In ladder diagram programs, all outputs are represented by:

a) Contact symbols

b) Coil symbols

c) a or b

d) None of the above


(ans. b)


14. List the advantages of PLCs over relay logic.