Page 251 - Programmable Logic Controllers, Fifth Edition

L1 Inputs Ladder logic program Output L2
Count PB
CTU
Count PB COUNT UP CU PL1
Counter C5:1
Preset 000 DN
Accumulated 000
Reset PB

MOV
MOVE
N7:10 Source N7:10

Destination C5:1.PRE

C5:1/DN PL1

Reset PB C5:1
RES

Figure 10-50 Program for Problem 2.

Inputs Ladder logic program Output
L1 EQU L2
S1 PL1
EQUAL
Source A N7:112
S1 PL1
Source B 004

N7:112

Thumbwheel switch
Figure 10-51 Program for Problem 4.

5. Study the data compare program in Figure 10-52 6. Write a program to perform the following:
and answer the following questions: a. Turn on pilot light 1 (PL1) if the thumbwheel
a. List the values for the thumbwheel switch that switch value is less than 4.
would allow the pilot light to turn on. b. Turn on pilot light 2 (PL2) if the thumbwheel
b. If the value in the word N7:112 is 003 and switch switch value is equal to 4.
S1 is open, will the pilot light turn on? Why? c. Turn on pilot light 3 (PL3) if the thumbwheel
c. Assume that source B is addressed to the accu- switch value is greater than 4.
mulated count of an up-counter. With S1 closed, d. Turn on pilot light 4 (PL4) if the thumbwheel
what setting of the thumbwheel switch would be switch value is less than or equal to 4.
required to turn the pilot light off when the ac- e. Turn on pilot light 5 (PL5) if the thumbwheel
cumulated count reaches 150? switch value is greater than or equal to 4.

232 Chapter 10 Data Manipulation Instructions

pet73842_ch10_207-233.indd 232 03/11/15 4:03 PM