DATA HANDLING
1.
(a) Give an example of a Data Transfer command
(b) Give an example of a Data Comparison command
(c) What is involved with a data compare instruction such a 'Less Than'
2. Study the data transfer program in Figure 10-44, and answer the following questions:
a. When 51 is off, what decimal number will be stored in integer word address N7:13 of the MCV instruction?
b. When S1 is on, what decimal number will be stored in integer word address N7:112 of the Moir: instruction?
c. When S1 is on, what decimal number will appear in the LED display?
d. What is required for the decimal number 216 to appear in the LED display? e hck /To,. ca-1:10;a1 thi,43 crck,
e. What two additional instructions are required for this data transfer operation to be completed?
3. (a) What are the four basic math functions that can be performed on some PLCs? (b) Would math instructions be classified as input or output instructions?
4. Design a program that will take an accumulated value of an ON Timer TIM1- and display it on a 4 digit BCD format of LED's. Use address 0: 023 for the LED's. Include the provision to change the preset value of the timer from a set of 4-digit BCD thumbwheels when input A is true. Use address 1:012 for the thumbwheels.
SEQUENCERS
5. (a) For what types of operations are output sequencer instructions (SQO) most suitable? (b) What is the advantage of sequencer programming over conventional programming methods?
(c) Explain the difference between an event driven and a time driven sequencer.
(d) Explain the purpose of the mask word when used in the sequencer function.
6. Using a Output Sequencer instruction - SQO- develop a program that will operate the following sequence of actions for 6 cylinders.
These cylinders are hooked up to the last six terminal points on the 16 bit output rack 0:013 (i.e. 0:013.10 to 0:013.15). The other terminal points on this output rack are to be masked from any control by the sequencer. The cylinders are all spring returned and solenoid energized to extend.
The time between each step is to be 3 seconds.
• All cylinders to retract
• Cylinder 1 to extend
• Cylinder 1 retract and cylinder 3 extend
• Cylinder 2 extend and cylinder 5 extend
• Cylinder 4 extend and cylinder 2 retract
• Cylinder 3 retract and cylinder 2 retract
• Cylinder 3 retract and cylinder 5 retract
• Cylinder 6 extend and cylinder 4 retract
• Cylinder 6 retract
• Sequence repeats
CONTROL INSTRUCTIONS
7. (a) State how the status of the output devices within a fenced zone will be affected when the MCR instruction transitions from False to True (i.e. logic HI, 'energized' state).
(b) State how the status of the output devices within the fenced zone will be affected when the MCR instruction transitions from True to False (i.e. logic LO, 'de-energized state).
(c) What is the main advantage of the Jump instruction?
(d) What is the purpose of the Label (LBL) instruction in the Jump to Label instruction pair?
(e) When the jump-to-label instruction is executed, in what way are the jumped rungs affected?
(f) There are two types of jump-to-subroutine instructions. What are they?
8 Answer the questions, in sequence, for the MCR program in Figure 9-26, assuming the program has just been entered and the PLC is placed in the RUN mode with all switches turned off.
a. Switches 52 and S3 are turned on. Will outputs PL1 and PL2 come on? Why?
b. With switches S2 and 53 still on, switch S1 is turned on. Will output PL1 or PL2 or both come on? Why?
c. With switches 52 and 53 still on, switch Si is turned off. Will both outputs PO and PL2 de-energize? Why?
d. With all other switches off, switch S6 is turned on. Will the timer time? Why?
e. With switch S6 still on, switch 55 is turned on. Will the timer time? Why?
f. With switch S6 still on, switch 55 is turned off. What happens to the timer? If the timer was an RTO type instead of a TON, what would happen to the accumulated value?
Answer the questions, in sequence, for Figure 9-29. Assume all switches are turned off after each operation.
a. Switches 52, S12, and 55 are turned on in order. Will output PL5 be energized? Why?
b. All switches except S7 are turned off. Will RIO start timing? Why?
c. Switches S3 and 58 are turned on in order. Will pilot light PL2 come on? Why?
d. When will timer TON function?
e. Assume all switches are turned on. In what order will the rungs be scanned?
f. Assume all switches are turned off. In what order will the rungs be scanned?
