Page 92 - Programmable Logic Controllers, Fifth Edition - Mobile version

A A
B B
C Y
D C
Y
(a) D

E
A F

B
(f )
C Y
Figure 4-31 (Continued )

3. The logic circuit of Figure 4-32 is used to activate an
D
alarm when its output Y is logic HIGH or 1. Draw a
(b)
truth table for the circuit showing the resulting out-
put for all 16 of the possible input conditions.
4. What will be the data stored in the destination
A address of Figure 4-33 for each of the following
logical operations?
B a. AND operation
Y b. OR operation
C c. XOR operation
(c) 5. Write the Boolean expression and draw the gate
logic diagram and typical PLC ladder logic dia-
gram for a control system wherein a fan is to run
only when all of the following conditions are met:
A • Input A is OFF

B • Input B is ON or input C is ON, or both B and C
are ON
• Inputs D and E are both ON
C • One or more of inputs F, G, or H are ON

A
D Y
B Alarm
Y
E C

(d) D
Figure 4-32 Logic circuit for Problem 3.

A Source A 0 00 0000 01 0 1 01 01 0

B
Y Source B 0 00 00000 111 01 01 1
C
D
Destination
(e)
Figure 4-31 Logic gate circuits for Problem 2. Figure 4-33 Data for Problem 4.

Fundamentals of Logic Chapter 4 73

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