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1. Describe the four basic parts of any programmable controller.
2. Explain the operation of a PLC up counter and down counter.
3. Discuss the differences between a program in a programmable controller and a BASIC or Fortran program.
4. Explain the four things that occur when the PLC processor scans its program.
5. Discuss the advantages a PLC controlled system would have over a hard-wired relay-type control system if you wanted to add one more photoelectric switch and output to detect a medium-sized box in the box sorting system.
6. Explain the function of an input module and how it completes this function. (Include the type of circuit you would find in an input module.)
7. The input module has a status indicator for each input circuit. Explain how the status indicator is used in troubleshooting.
8. Explain the function of an output module and how it completes this function. (Include the type of circuit you would find in an output module.)
9. Explain the function of an internal control relay.
10. Explain how a set of PLC contacts can be used more than once in a program.
11. Discuss the classifications of PLCs according to size.
AMAZON multi-meters discounts AMAZON oscilloscope discounts1. _______ One advantage of all PLCs is that you can use contacts with the same address more than once in the program.
2. _______ When the PLC processor is in the run mode, it does not execute its scan cycle.
3. _______ A mnemonic is a timer whose time delay is controlled by air pressure.
4. ______ When a timer in a PLC program will not time, you should suspect the timer is broken and you will need to program a replacement timer.
5. _______ A control relay (memory coil) in a PLC program is different from an output instruction in that its signal does not control a circuit in an output module and it's used mainly to determine logic conditions.
1. A latch coil _____.
a. maintains its state when power is interrupted.
b. is only sealed in and returns to reset when power is interrupted.
c. requires an unlatch coil with the same address.
d. both a and c.
2. A seal-in circuit such as the one used for a start/stop circuit ________
a. maintains its state when power is interrupted.
b. does not maintain its state when power is interrupted and must be energized after
power has been returned by depressing the normally open push button.
c. requires an unlatch coil to de-energize the output.
3. When the input contact that enables a retentive timer (RTO) is opened, the accumulated value in the timer will _______
a. reset (go to zero).
b. freeze (remain at its present value).
c. go to an undetermined value and the timer must be reset manually.
4. A non-retentive timer has its accumulative value reset _______
a. any time the enable contacts are opened.
b. only when the reset for the timer is HI.
c. any time the accumulative value in the timer exceeds 99.
5. When the PLC processor is in the program mode _______
a. it executes its scan cycle.
b. it does not execute its scan cycle.
c. it's impossible to tell whether the processor is executing its scan cycle because you are not on line.
1. Enter the conveyor box sorting program in ill. 6 in a programmable controller and execute the inputs to watch the program operate. Describe the operation of each output.
2. Enter an on-delay timer and an off-delay timer in your PLC and describe the following:
preset time, accumulative time, what must occur for the timer to run, what must occur for the timer to time out, and which contacts change when the timer times out.
3. Enter an up counter and a down counter in your PLC and describe the following: preset value, accumulative value, what must occur for each counter to count, what occurs when the counter’s preset and accumulative values equal, what happens when the counter’s accumulative value reaches 9999, which contacts change when the counter reaches its preset value, and which contacts change when the counter reaches 9999.
4. Program a timer and cascade the counters that will keep track of seconds, minutes, hours, and days.
5. Program a sequencer into your PLC and describe its operation. Your teacher may give you an example program or use the sequencer for the carbon brush application.
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Friday, February 18, 2022 11:52