Deck 9: Sequencer and Shift Register Instructions

Question 1

An event-driven sequencer operates in a manner similar to a mechanical drum switch that increments automatically after a preset time period.

Answer 1

False

Question 2

Shift registers are often used for tracking parts on a production line.

Answer 2

True

Question 3

With a bit shift register, the status data (1 or 0) is shifted automatically through the register from one bit address to the next.

Answer 3

True

Question 4

A time-driven sequencer advances to the next step by an external pulsed input.

Question 5

Sequencers are programmed exactly the same for all PLC types.

Question 6

The mask parameter is the address of the sequencer file.

Question 7

Sequencer instructions simplify your ladder program.

Question 8

The file word selectively screens out data from the sequencer word file to the output word.

Question 9

When a sequencer operates on an entire output word, all outputs associated with the word are required to be controlled by the sequencer.

Question 10

Sequencer instructions are normally nonretentive.

Question 11

Bits of an output word not used by the sequencer can be used elsewhere in your program.

Question 12

Many sequencer instructions reset the sequencer automatically to step 1 on completion of the last sequence step.

Question 13

There is usually no limit to the number of external outputs and steps that can be operated on by a single sequencer instruction.

Question 14

As a programmed sequencer advances through its steps, binary information is transferred from the sequencer file to the output word.

Question 15

Mechanical sequencer switches are often referred to as drum switches.

Question 16

Sequencer switches can be used for processes that require a repeatable operating pattern.

Question 17

Due to the way in which a sequencer instruction operates, all output points must be on a single output module.

Question 18

To program a sequencer, binary information is entered into a number of random memory bits.

Question 19

The sequencer control parameter is where the status bits, length, and instantaneous position are stored.

Question 20

In general the two types of shift instructions are bit shift up and bit shift down.

Question 21

For the sequencer instruction shown, in step 1 ____ will be energized.

A)outputs O:2.0, O:2.5, O:2.8, O:2.11, O:2.12, and O:2.15
B)outputs O:2.2, O:2.3, O:2.10, O:2.12, and O:2.14
C)outputs O:2.0, O:2.4, O:2.6, O:2.7, O:2.9, O:2.10, and O:2.13
D)all outputs

Question 22

For the SQO instruction shown, the ____ is the address of the word used to selectively screen out data.

A)File
B)Length
C)Mask
D)Destination

Question 23

If you wanted to produce an external output when a certain bit in a shift register is on, you would program a rung with an examine for on instruction corresponding to the bit address.

Question 24

The information for each PLC sequencer step is entered into:

A)the output module.
B)the input module.
C)the programmer.
D)a word file.

Question 25

The sequencer instruction shown reads the 16 bit data file words:

A)one bit at a time.
B)one word at a time.
C)two bits at a time.
D)two words at a time.

Question 26

Which of the following would not be classified as a sequencer switch?

A)Rotary switch
B)Pressure switch
C)Drum switch
D)Stepper switch

Question 27

For the sequencer instruction shown, in step 2 ____ will be energized.

A)outputs O:2.0, O:2.5, O:2.8, O:2.11, O:2.12, and O:2.15
B)outputs O:2.2, O:2.3, O:2.10, O:2.12, and O:2.14
C)outputs O:2.0, O:2.4, O:2.6, O:2.7, O:2.9, O:2.10, and O:2.13
D)all outputs

Question 28

The equivalent sequencer data for step 2 of the sequencer shown would be:

A)0000000000000000
B)1111111111111111
C)0111001010101010
D)1111 0000 0011011

Question 29

As the sequencer advances through the steps, data is transferred:

A)through the sequencer file from B3:0 to B3:4.
B)through the sequencer file from B3:4 to B3:0.
C)from the output word to the sequencer file.
D)from the sequencer file to the output word.

Question 30

For the SQO instruction shown, the ____ is the number of steps of the sequencer file.

A)Position
B)Control
C)Mask
D)Length

Question 31

You can program a shift register instruction to shift only 1s through the register.

Question 32

For the sequencer instruction shown, in step 3 ____ will be energized.

A)outputs O:2.0, O:2.5, O:2.8, O:2.11, O:2.12, and O:2.15
B)outputs O:2.2, O:2.3, O:2.10, O:2.12, and O:2.14
C)outputs O:2.0, O:2.4, O:2.6, O:2.7, O:2.9, O:2.10, and O:2.13
D)all outputs

Question 33

When you program a shift register instruction, you can shift data only to the left.

Question 34

As the PLC sequencer advances through its steps, information is transferred from:

A)the output module to the input module.
B)the input module to the output module.
C)the programmer to the processor.
D)the word file to the output word.

Question 35

For the sequencer instruction shown, ____ outputs are to be controlled from one 16-point output module.

A)6
B)15
C)16
D)24

Question 36

For the SQO instruction shown, the ____ bit is set after the last word in the sequencer file is transferred.

A)Position
B)Control
C)EN
D)DN

Question 37

Shift registers cannot be used to control processes where parts are shifted continually from one position to the next.

Question 38

For the Sequencer Output (SQO) instruction shown, the ____ is the address of the output word to which the sequencer moves the data.

A)Control
B)Destination
C)Position
D)None of these are correct

Question 39

For the SQO instruction shown, the ____ is the starting address for the registers that contain the data to be transferred.

A)File
B)Control
C)Mask
D)Length

Question 40

Sequencer switches are used whenever:

A)a counter function is required.
B)a timer function is required.
C)a time-delay function is required.
D)a repeatable operating pattern is required.

Question 41

When the sequencer instruction shown is at step ___, outputs O:2/2 and O:2/3 will be on and all the rest will be off.

A)1
B)2
C)3
D)4

Question 42

The sequencer shown operates whenever

A)input A is false.
B)input A is true.
C)the PLC is in the run mode.
D)the PLC is in the program mode.

Question 43

The sequencer shown advances its position whenever:

A)S1 makes a false-to-true transition.
B)S2 makes a false-to-true transition.
C)the PLC is in the run mode.
D)either S1 makes a false-to-true transition or S2 makes a false-to-true transition.

Question 44

For the sequencer instruction shown, all unmasked bits:

A)can be used elsewhere in the program.
B)cannot be used elsewhere in the program.

Question 45

A single sequencer instruction may have an upper limit on:

A)the number of steps that can be programmed.
B)the number of external outputs that can be programmed.
C)the number of times the operating cycle can be actuated.
D)both the number of steps that can be programmed and the number of external outputs that can be programmed.

Question 46

When the sequencer instruction shown is at step 1, the binary information transferred into word O:2 would be:

A)010001.
B)001010.
C)100001.
D)None of these are correct.

Question 47

When using a time-driven sequencer, the sequencer advances to the next step:

A)when the preset value equals the accumulated value.
B)when the preset value is less than the accumulated value.
C)for every true-to-false transition of the sequencer rung.
D)for every false-to-true transition of the sequencer rung.

Question 48

The sequencer instruction shown controls ____ bits of output word O:2.

A)2
B)6
C)10
D)15

Question 49

The sequencer program shown is:

A)motor-driven.
B)time-driven.
C)event-driven.
D)gear-driven.

Question 50

Normally, sequencer instructions are retentive. This means that, if you are at step 3 of a 10-step sequencer and power to your system is lost, when power is restored the sequencer will:

A)return to step 3.
B)increment to step 4 automatically.
C)reset to step 1 automatically.
D)advance to step 10 automatically.

Question 51

When the sequencer shown is functioning, the circuit increments automatically through the ____ steps of the sequencer at ____ intervals.

A)five, 3 second
B)six, 3 second
C)five, 3 minute
D)six, 3 minute

Question 52

A program modification is to be made to the sequencer shown that requires outputs O:2/12, O:2/13, O:2/14, and O:2/15 to be energized at step 3. This would require:

A)bits 12, 13, 14, and 15 of word B3:22 to be set to 1.
B)bits 13, 14, and 15 of word B3:23 to be set to 1.
C)bits 12, 14, and 15 of word B3:24 to be set to 1.
D)bits 14 and 15 of word B3:25 to be set to 1.

Question 53

For each bit that the sequencer shown is to control, the corresponding bit of mask must be set to:

A)0.
B)1.
C)positive.
D)negative.

Question 54

The sequencer program shown is:

A)motor-driven.
B)time-driven.
C)event-driven.
D)gear-driven.

Question 55

For each position of the sequencer shown, data are copied from file #B3:0 through the ____ word to the destination.

A)Mask
B)Control
C)Position
D)Length

Question 56

When the sequencer shown is at position 2, which output(s) will be energized?

A)02/12
B)0:2/13
C)0:2/12 and 0:2/13
D)0:2/14

Question 57

When the sequencer position parameter reaches 4, the ____ bit is set to 1.

A)Control
B)EN
C)DN
D)all of these

Question 58

The sequencer program shown advances to the next position on each:

A)true to false transition of the sequencer rung.
B)false to true transition of the sequencer rung.
C)on power up of the PLC.
D)on power down of the PLC.

Question 59

For the sequencer instruction shown, in step 4 ____ will be energized.

A)outputs O:2.0, O:2.5, O:2.8, O:2.11, O:2.12, and O:2.15
B)outputs O:2.2, O:2.3, O:2.10, O:2.12, and O:2.14
C)outputs O:2.0, O:2.4, O:2.6, O:2.7, O:2.9, O:2.10, and O:2.13
D)all outputs

Question 60

The sequencer input instruction shown is true whenever the unmasked input data are ____ the data stored in the sequencer file.

A)matched to
B)greater than
C)less than
D)greater than or equal to

Question 61

In this example, the data at position ____ matches the unmasked input data making the PL1 output ____.

A)2, true
B)2, false
C)4, true
D)4, false

Question 62

When the BSL rung goes from false to true, the data block is shifted:

A)one bit position to a lower bit number.
B)one bit position to a higher bit number.
C)two bit positions to a lower bit number.
D)two bit positions to a higher bit number.

Question 63

When the SQI instruction is paired with the SQO instruction as illustrated:

A)the same control address, length value, and position value are used for each instruction.
B)the sequencer input instruction is indexed by the sequencer output instruction.
C)it allows input and output sequences to function in unison.
D)all of these.

Question 64

A matrix is a three-dimensional rectangular array of quantities.

Question 65

The sequencer load instruction shown:

A)does not function during the machines normal operation.
B)replaces manual loading of data into the sequencer file.
C)does not use a mask.
D)all of these.

Question 66

The data block of the program contains ____.

A)20 words
B)32 words
C)20 bits
D)32 bits

Question 67

Each time the BSL executes, the last bit:

A)is shifted out of the array.
B)reset to 0.
C)set to 1.
D)is shifted to the start of the array.

Question 68

For the word shift register program shown, the ____ instruction loads logic words into FIFO stack.

A)FFL
B)FFU
C)EM
D)EN

Question 69

In a word shift register, the data are shifted out ___bit(s) at a time.

A)1
B)2
C)4
D)16

Question 70

For the bit shift left (BSL) register shown, file length is given in:

A)words.
B)bits.
C)steps.
D)files.

Question 71

A bit shift register operates synchronously, in that:

A)information is shifted one bit at a time within a word or words.
B)for every bit shifted in, one is shifted out.
C)the data entered must be shifted the length of the register before it is available to be shifted out.
D)all of these.

Question 72

Data enter the FIFO file from ____ on a false-to-true transition of input A.

A)R6:0
B)N7:10
C)N7:12
D)N7:11

Question 73

A common application for a shift register would be:

A)tracking parts.
B)controlling machine or process operations.
C)inventory control.
D)all of these.

Question 74

When all the outputs in a word may not be required for a specific sequencer process, it is possible to mask the outputs that are not needed.

Question 75

All bits in the unused portion of the last word of the file:

A)can be used elsewhere in the program.
B)can only be used elsewhere in the program if masked.
C)can only be used elsewhere in the program if not masked.
D)should not be used elsewhere in the program.

Question 76

A false-to-true transition of input B causes all data in the FIFO file to:

A)shift one position toward the ending address of the file.
B)shift one position toward the starting address of the file.
C)set all data in the file to 1.
D)rest all data in the file to 0.

Question 77

Momentary actuation of ____ causes the BSL instruction shown to execute.

A)the limit switch
B)the sensor
C)either the limit switch or sensor
D)both the limit switch and the sensor

Question 78

The sequencer load instruction shown ____data from the source to the sequence file.

A)adds
B)subtracts
C)copies
D)negates

Question 79

A bit shift register shifts bits:

A)serially from bit to bit.
B)serially between words.
C)randomly from bit to bit.
D)randomly between word.

Question 80

Sequencers that advance automatically are called event-driven sequencers.