Page 224 - Programmable Logic Controllers, Fifth Edition - Mobile version

3. Answer the questions, in sequence, for the jump-
to-subroutine and return program in Figure 9-31. 4. Answer the questions, in sequence, for Figure 9-32.
Assume all switches are turned off after each
Assume all switches are turned off after each operation.
operation. a. Switches S2, S12, and S5 are turned on in order.
a. Switches S1, S3, S4, and S5 are all turned Will output PL5 be energized? Why?
on. Which pilot light will not be turned on? b. All switches except S7 are turned off. Will RTO
Why? start timing? Why?
b. Switch S2 is turned on and then switch S4 c. Switches S3 and S8 are turned on in order. Will
is turned on. Will output PL3 be energized? pilot light PL2 come on? Why?
Why? d. When will timer TON function?
c. To what rung does the RET instruction return the e. Assume all switches are turned on. In what order
program scan? will the rungs be scanned?
f. Assume all switches are turned off. In what
order will the rungs be scanned?

Ladder logic program
Inputs Main program file 2 Outputs
L1
S1 PL1 L2
S1 1 PL1
S2 JSR
S2 JUMP-TO-SUBROUTINE
2
SBR file number U:3 PL2
S3
S3 PL2
3 PL3
S4
S5 PL4
S5 4 PL4

Subroutine file 3
S4 PL3
SBR
5 SUBROUTINE
RET
6 RETURN

Figure 9-31 Program for Problem 3.

Program Control Instructions Chapter 9 205

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