20.6 PRACTICE PROBLEMS
1. Draw a ladder diagram that will cause output D to go true when switch A and switch B are closed or when switch C is closed. The devices are wired to the following locations.
Input A is 001
Input B is 002
Input C is 003
Output D is 201
2. Draw a ladder diagram that will cause output D to be on when push button A is on, or either B or C are on.
Input A is 001
Input B is 002
Input C is 003
Output D is 201
4. Make a simple ladder logic program that will turn on the outputs with the binary patterns when the corresponding buttons are pushed. Assume that the outputs are from 200 to 207 and that 200 is the LSB)
11011011 (input 101)
10101010 (input 102)
10010010 (input 103)
7. Given the truth table below
a) find a Boolean algebra expression using a Karnaugh map.
b) draw a ladder diagram using the truth table (not the Boolean expression).
8. Simplify the Boolean expression below.
ans. =C
9. Given the Boolean expression a) draw a digital circuit and b) a ladder diagram (do not simplify).
10. a) Construct a truth table for the following problem.
i) there are three buttons A, B, C.
ii) the output is on if any two buttons are pushed.
iii) if C is pressed the output will always turn on.
b) Develop a Boolean expression.
c) Develop a Boolean expression using a Karnaugh map.
11. a) Given the following truth table, show the Boolean combinations that would give a result of 1.
b) Write the results in a) in a Boolean equation.
c) Simplify the Boolean equation in b)
12. Develop the simplest Boolean expression for the Karnaugh map below,
a) graphically.
b) by Boolean Algebra
13. Setup the Karnaugh map for the truth table below.
14. a) Develop the Boolean expression for the circuit below.
b) Simplify the Boolean expression.
c) Draw a simpler circuit for the equation in b).
15. Is the ladder logic below for,
a) AND
b) OR
c) both a) and b)
d) none of the above
(ans. a)
16. Simplify the following Boolean equations,
17. Simplify the following boolean equations
18. Convert the following ladder logic to a karnaugh map.
19. Simplify the following and implement the original and simplified equations with gates and ladder logic.
27. Short answer
a) Write the simplest Boolean equation for the karnaugh map below,
28. Given a system that is described with the following equation,
a) Simplify the equation using Boolean Algebra.
b) Implement the original and then the simplified equation with a digital circuit.
c) Implement the original and then the simplified equation in ladder logic.
d) Implement the simplified equation in a Basic Stamp program. Assume the inputs and outputs are on pins A=1, B=2, C=3, D=4, E=5, X=6)
29. Given the truth table below find the most efficient ladder logic to implement it. Use a structured technique such as Boolean algebra or Karnaugh maps.
30. For the following Boolean equation,
a) Write out the logic for the unsimplified equation.
b) Simplify the equation.
c) Write out the ladder logic for the simplified equation.
31. Use a karnaugh map to simplify the following truth table, and implement it in ladder logic.
32. Convert the following Boolean equation to the simplest possible ladder logic.
