Plc Unit 3 Sem 2

Front 1

Word level math instructions are utilized to perform arithmetic functions. Basic word level math instructions include: (4)

(4)

Back 1

-Add (ADD) -Subtract (SUB) -Multiply (MUL) -Divide (DIV)

Front 2

Other word level math instructions include: (4)

Back 2

Compute (CPT)

Square Root (SQR)

Negate (NEG)

Scale (SCL)

Front 3

Evaluates an expression, and then stores the value in a specified destination. This instruction takes more processing power/scan time than those previously discussed.

Back 3

Compute (CPT)

Front 4

Changes the sign of the source and stores the value in a specified destination.

Back 4

Negate (NEG)

Front 5

Calculates the square root of the source and stores the value in a specified destination.

Back 5

Square Root (SQR)

Front 6

The scale instruction is used to enlarge or reduce very small or very large numbers by the rate value.

Back 6

Scale (SCL)

Front 7

File level arithmetic functions are taken care of using the ____ instruction.

Back 7

FAL

Front 8

One type of numerical I/O interface are the multibit digital devices, which ___________. These types of devices are primarily suited for BCD inputs and outputs.

Back 8

allow groups of digital inputs to be read as a whole unit.

Front 9

In some circumstances, where numerical I/O interfaces are not available, the following instructions are used to convert between decimal and BCD values.

Back 9

Convert to BCD (TOD)

Convert from BCD (FRD)

Front 10

These instructions are used to enable/disable blocks of program logic, or move the program scan from one location to another.

Back 10

program control instructions.

Front 11

____ instruction functions in a similar fashion to electromechanical master control relays. The intent of the master control relay is to disable a relay control circuit as long as the relay has not been energized.

Back 11

Master Control Reset

Master Control Reset

Front 12

MCR instruction is typically used to replace an electromechanical MCR relay.

True or False

Back 12

False

MCR instruction is not typically used to replace an electromechanical MCR relay.

Front 13

Also note that the MCR instruction is ____ addressed

Back 13

Not

Front 14

All rungs that exist between the two ___ instructions are part of a fenced zone, with the conditional ___ being the start fence, and the unconditional ___ being the end fence.

Back 14

MCR, MCR, MCR

Front 15

When the conditional MCR does not have logic continuity, the following occurs to the rungs within the fenced zone. (2)

Back 15

-All nonretentive outputs are de-energized, regardless of the state of their input conditions. -All retentive outputs will remain in their last state.

Front 16

Assuming that the Input A switch is opened, the associated XIC instruction used as a condition for the first MCR instruction will go false. When the MCR instruction loses logic continuity, the following occurs.

Back 16

Output A (nonretentive) is in the de-energized state. Output B (retentive) is in the energized state.

Front 17

The following guidelines should be observed when working with the MCR instructions:

Back 17

-Multiple fenced zones can be setup. However, never overlap two zones. Overlapping zones, or jumping to a rung within a MCR zone can cause unexpected operation, and could be potentially damaging. -It is generally advisable to avoid using latch/unlatch instructions within an MCR zone. Because these outputs will remain in their last state, and may remain energized when they are not intended to do so. -Timer and counter operation will cease when an MCR zone is de- energized. TOF instructions will begin timing when in a false MCR zone. Use caution.

Front 18

The ____ instruction is used to bypass portions of the ladder program. Sections of the program that are jumped will not be evaluated/executed during the current scan.

Back 18

Jump (JMP)

Front 19

The JMP instruction is always paired with a ____ instruction that serves as a target. Both are addressed (within the SLC-500 family of AB controllers) to Q2:0 through Q2:255.

Back 19

label (LBL)

Front 20

The following guidelines/notes should be followed when working with the JMP instruction.

Back 20

-Jumping backwards is possible. However, it should be done with caution. If it is done excessively, scan time can become extended, which may trigger the PLC’s internal watchdog timer. This will cause the PLC to enter a faulted state. -Although the way the JMP instruction handles inputs is similar to the MCR instruction, it differs with outputs. The MCR leaves only retentive outputs in their last state. The JMP instruction leave all outputs in their last state. -Avoid jumping into MCR zones. Jumping into a de-energized MCR zone will actually cause the portion of the program between the LBL instruction and the second MCR instruction to be executed without consideration of the first conditional MCR.

Front 21

____ are short programs that are used by the main program to perform a specific function. ____ are stored in program files numbered LAD 3 through LAD 255.

Back 21

Subroutines, Subroutines

Front 22

There are three instructions associated with subroutines:

Back 22

Jump to Subroutine (JSR)

Subroutine (SBR)

Return (RET)

Front 23

The first input condition entered in the subroutine. It serves to identify the file as a subroutine. It is always true, and is actually optional, though recommended.

Back 23

Subroutine (SBR):

Front 24

An output instruction that causes the scan to jump to a specified subroutine file (U3 through U255) when input conditions are true.

Back 24

Jump to Subroutine (JSR):

Front 25

An output instruction that causes the scan to return to the main program. It can be a conditional, or unconditional output depending on the desired operation of the subroutine.

Back 25

Return (RET):

Front 26

The more subroutines added, the longer/shorter the scan time necessary to execute them all. In other words, time spent in subroutines is time not spent in the main program.

Back 26

Longer

Front 27

Similar to the immediate input (IIN) instruction , the ____ instruction is used to exit the program scan prior to the I/O scan. This allows for a critical/time-sensitive output to be updated in the output image table.

Back 27

immediate output (ION)

Front 28

Despite the many safegaurds inherent to many of today’s PLCs, ____ fail safe provisions and disconnecting means CANNOT be replaced.

Back 28

hard-wired

Front 29

In addition, a hard-wired MCR is provided for manual control of the controller power supply. These devices should never be bypassed. Doing so introduces

Back 29

significant personnel and equipment risk.

Front 30

In addition to relay control safety provisions, some PLCs are considered safety class PLCs. This PLCs feature ____, ____ and ____ for the purpose of built in redundancy. These components are continuously monitored by the PLC watchdog circuit to detect failures.Additionally, built-in I/O testing functionality exists to monitor I/O operations.

Back 30

additional processors, FLASH, RAM memory

Front 31

Data manipulation instructions fall into two broad categories:

Back 31

data transfer instructions, and data compare instructions.

Front 32

Data manipulation instructions operate on either a ____, or a ____. Bit level operation is not typical of these instructions.

Back 32

word/register level, or a file/table level

Front 33

At its simplest, data transfer instructions involve

Back 33

moving information from one spot in memory, to another spot specified by the instruction.

Front 34

The ____ instruction is used to transfer the data from one word/register to a new, specified location.

Back 34

Move (MOV)

Front 35

Similar to the moveinstruction, is the ____ instruction. The key difference between the two instructions, is that the move with mask instruction allows the user to determine which portions of data are passed to the destination file.

Back 35

Move with Mask (MVM)

Front 36

The ____ instruction is similar to the move instruction. It differs in that it can be used to move data within a single word.

Back 36

bit distribute (BTD)

Front 37

Keep in mind, if the length of the data being moved, and the destination bit exceed the 16-bit size of the word, the data will

Back 37

NOT wrap, and will be lost.

Front 38

Some data transfer instructions, such as the ____, ____ and ____ instructions are used to move groups of words (or files) from place to place, or to perform file arithmetic.These data transfers can involve moving the data of one word into a group of words, from file to file, or the data from a file to a single word.

Back 38

FAL, COP, and FLL

Front 39

The ____ instruction is used to duplicate the data in file, to a different file specified by the user program.

Back 39

Copy (COP)

Front 40

The ____ instruction can be used when working with a word-to-file data transfer.

Back 40

Fill (FIL)

Front 41

The ____ instruction is more complex than the previous to file-level data transfer instructions. The ____ can be used not only to move information from location to location, but can also be used to perform calculations from the data stored within the file.

Back 41

File Arithmetic and Logic (FAL), FAL instruction

Front 42

Data Compare instructions are used to ___________________________________

They do not move, or change the data stored in the specified words. They are utilized as input instructions, and will be in a true state based on the logic of the individual instruction.

Back 42

compare the numerical data stored in specified words.

Front 43

Equal:

Back 43

Compares two words, or one word to a preset value. The instruction is true if A = B.

Front 44

Not Equal:

Back 44

Compares two words, or one word to a preset value. The instruction is true if A != B.

Front 45

Greater Than:

Back 45

Compares two words, or one word to a preset value. The instruction is true if A > B.

Front 46

Less Than:

Back 46

Compares two words, or one word to a preset value. The instruction is true if A < B.

Front 47

Greater Than or Equal:

Back 47

Compares two words, or one word to a preset value. The instruction is true if A >= B.

Front 48

Less Than or Equal:

Back 48

Compares two words, or one word to a preset value. The instruction is true if A <= B.

Front 49

Inner Limit:

Back 49

Compares a test value to an upper and lower limit. If the test value is between upper and lower limit, the instruction is true.

Front 50

Outer Limit:

Back 50

Compares a test value to an upper and lower limit. If the test value is outside the two limits, the instruction is true.

Front 51

Data compare instructions can be used to drastically reduce the number of ____ utilized in a circuit.

Back 51

timers

Front 52

The term ____ control refers to a process in which feedback is utilized to control a monitored system parameter. These parameters include pressure, flow, temperature, level, or speed.

Back 52

closed-loop

Front 53

____ control is the simplest form of closed-loop control, and compares the input value to a system set-point.

Back 53

Set-point

Front 54

____ control although it is generally inexpensive, it is also inaccurate due to the fact that the controlled variable will often over- or undershoot the set-point. Even with dead band the system may still cycle in an undesirable fashion.

Back 54

On/Off

Front 55

___ control produces outputs based on the magnitude, duration and rate of change of system error. Simply put: Proportional = Past Error Integral = Current Error Derivative = Future Error

Back 55

PID