Chapter 5 Lab & Exercises

Exercises

1.  *A car wash with two bays has a pump supplying water pressure to the spray heads. If both bays are in use or if one bay requires a second set of heads for a tall truck, a second pump is required. The Tall truck request is made via a selector switch for each bay. If both bays are in use with a tall truck in one or both bays, a third pump is required.

2. *A design change was noticed by the engineer who saw that the xo on the selector switch for Bay 2’s Tall Truck Selector switch was really wired ox. Would this change affect the Input Signal Assignment, Boolean equations, or ladder logic? If so, how?
3.  Which pump of problem #1 will be on the most? Is this a good design? Describe how you would change the design if you do not agree that this is a good design.
4. Develop a logic statement in Boolean, FBD and Ladder to turn on an output when switch X and switch Y are energized or when switch Z is energized:
5. Develop a logic statement in Boolean, FBD and Ladder to turn on an output when switch U is on or when only one of the two following is on: V energized, W energized.
6. Develop a logic statement in Boolean, FBD and Ladder to energize the engine start circuit when the key is in the ignition, all (3) front-passenger seat belts are engaged (in which a person is sitting), and all doors are closed (assume a 4-door car).
7. *Use the following ladder rung to answer the following three questions:

1. 1. 1. Write the DeMorgan of the circuit above using ladder format.
      2. Write the Boolean equivalent of the circuit above.
      3. Create a truth table and find the state of F for each condition of A-E.

8.  *Use the following ladder rung to answer questions a and b of #7, above:

9. *Use the following ladder rung to answer questions a and b of #7, above:

10. *Use the following ladder rung to answer questions a and b of #7 above:

Write as ladder logic the following Boolean expressions:

11. (a and not b and not c) equal output d
12. (a or not b) and (c or not d or not e) equal output f
13. *(a or not b or not c or not d) and (not e or not f) and (not g or h) equal output j
14.  (a or b) and c equal output d
15. Convert the following Allen-Bradley’s RSLogix 500’s B3: addresses from word/bit format to bit format:
    1. B3:0/2
    2. B3:2/5
    3. B3:10/9
    4. B3:6/15
16. Convert the following B: addresses from bit format to word/bit format:
    1. B3/20
    2. B3/8
    3. B3/56
    4. B3/211
17. *The attached buttons and coin slot sensors are part of an arcade game. Two games are in the same arcade box. One is a cheap game and one is a good game. If the player inserts quarters in any three of the four slots marked quarter 1 through quarter 4, and pushes the Request Cheap button, the cheap game starts. If the player puts quarters in all four of the quarter slots and pushes the Request Good button, the good game starts. Program rungs to energize a coil for starting the cheap game and a coil for starting the good game. The cheap game does not start if all four quarter slots are filled. Assume all state assignments for the slot sensors and buttons are equal to 1.

18. *Write the logic necessary to turn on the Change light if 55 cents is required for a candy bar and the rules similar to those of the lab are adhered to, that is, that 1, 2 or 3 coins can be ‘on’ when the request is pushed with the first is on before the second which is on before the third. Be as complete as possible:

19. *Write the DeMorgan of the circuit below using ladder format.

Lab 5.1 The Coin Changer

Implement a program to control a coin changer. A coin changer is built to return change plus dispense a $.35 candy bar. No more than three coins are to ever be used (There is no need to count the number of coins entered). Coins to be used are dimes and quarters. Write a program to accept or reject the sale based on the coins rendered. Coins rendered are checked by inputs on using push buttons or selector switches when the Request Candy Bar button is pushed.

Assume dime 2 is not allowed until dime 1 is on. Assume dime 3 is not allowed until dime 2 ison. That is, dimes enter by filling the slot for dime 1, then dime 2 and finally dime 3. The same sequence is used for quarters. Inputs are as follows:

Accept turns on with the Request Candy Bar input and enough money entered.
Change turns on with the Request Candy Bar input and an excess of money.
Reject turns on with the Request Candy Bar input when no money or not enough money is entered. Option 1: Change the price to $.45 for the candy bar.
Option 2: Change the price to $.55 for the candy bar. Here 4 coins may be used. (including 1 nickel)