Page 250 - Programmable Logic Controllers, Fifth Edition - Mobile version

18. Outline the process by which an analog output in-
terface module operates the field device connected 21. Compare the operation of the final control element
in on/off and proportional control systems.
to it. 22. Explain the meaning of the following terms as they
19. Compare the operation of open-loop and closed- apply to a PID control:
loop PLC systems. a. Process variable
20. Outline the control process involved with simple b. Set-point
PLC set-point control. c. Error
d. Control variable

CHAPTER 10 PROBLEMS

1. Study the data transfer program of Figure 10-49 after 25 off-to-on transitions of the count
and answer the following questions: PB input.
a. When S1 is open, what decimal number will 3. Construct a nonretentive timer program that will
be stored in integer word address N7:13 of the turn on a pilot light after a time-delay period. Use
MOV instruction? a thumbwheel switch to vary the preset time-delay
b. When S1 is on, what decimal number will be value of the timer.
stored in integer word address N7:112 of the 4. Study the data compare program of Figure 10-51
MOV instruction? and answer the following questions:
c. When S1 is on, what decimal number will ap- a. Will the pilot light PL1 come on whenever
pear in the LED display? switch S1 is closed? Why?
d. What is required for the decimal number 216 to b. Must switch S1 be closed to change the num-
appear in the LED display?
ber stored in source A of the EQU instruction?
2. Study the data transfer counter program of c. What number or numbers need to be set on
Figure 10-50 and answer the following questions: the thumbwheel in order to turn on the pilot
a. What determines the preset value of the light?
counter?
b. Outline the steps to follow to operate the
program so that the PL1 output is energized

Inputs Ladder logic program Output
L1 L2
S1
MOV
MOVE
S1
Source N7:112
Destination N7:13 N7:13

4
LED display
8 N7:112
5
Thumbwheel switch
Figure 10-49 Program for Problem 1.

Data Manipulation Instructions Chapter 10 231

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