Page 267 - Programmable Logic Controllers, Fifth Edition - Mobile version

CHAPTER 11 PROBLEMS

1. Answer each of the following with reference to the (3) N7:1
counter program shown in Figure 11-36. (4) Source B of the GEQ instruction
a. Assume the accumulated count of counters C5:0 d. Will output PL1 be energized at this point?
and C5:1 to be 148 and 36, respectively. State Why?
the value of the number stored in each of the fol- 2. Answer each of the following with reference to the
lowing words at this point: overfill alarm program shown in Figure 11-37.
(1) C5:0.ACC a. Assume that the vessel is filling and has reached
(2) C5:1.ACC the 300-lb point. State the status of each of the
(3) N7:1 logic rungs (true or false) at this point.
(4) Source B of the GEQ instruction b. Assume that the vessel is filling and has reached
b. Will output PL1 be energized at this point? the 480-lb point. State the value of the number
Why? stored in each of the following words at this
c. Assume the accumulated count of counters C5:0 point:
and C5:1 to be 250 and 175, respectively. State (1) I:012
the value of the number stored in each of the fol- (2) N7:1
lowing words at this point: c. Assume that the vessel is filled to a weight of
(1) C5:0.ACC 502 lb. State the status of each of the logic rungs
(2) C5:1.ACC (true or false) for this condition.

Inputs Ladder logic program Output
L1 L2
S1
CTU
COUNT-UP COUNTER CU
S1 PL1
Counter C5:0 DN
Preset 350
Accumulated 0
S2 S2 CTU
COUNT-UP COUNTER CU
Counter C5:1 DN
Preset 350
Reset Accumulated 0

ADD
ADD
Source A C5:0.ACC
Source B C5:1.ACC
Destination N7:1
PL1
GEQ
GREATER THAN OR EQUAL
Source A N7:1

Source B 350
Reset
C5:0
RES
C5:1
RES

Figure 11-36 Program for Problem 1.

248 Chapter 11 Math Instructions

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