Week 2: PLC Instructions Flashcards
(81 cards)
1
Q
What is the symbol for AND logic
A
2
Q
What is the operator for an AND logic
A
Multiplication
3
Q
What is the operator for an or logic
A
Addition
4
Q
What circuit configuration can be used to describe an AND logic
A
Series
5
Q
What circuit configuration can be used to describe an OR logic
A
Parallel
6
Q
What’s the mathematical expression for the XOR gate
A
(A * Bbar) + (Abar * B)
7
Q
What’s the symbol for OR logic
A
8
Q
What’s the symbol for AND logic
A
9
Q
What’s the symbol for NAND logic
A
10
Q
What’s the symbol for NOT logic
A
11
Q
What’s the symbol for XOR logic
A
12
Q
What are the classes of PLC instructions
A
Relay Logic, Arithmetic Logic, Data handling logic, Timer Instructions, Counter Instructions.
13
Q
What does the XIC and XIO contact work
A
It tells the CPU to examine a bit at the memory location specified by the address number listed with the symbol. The referenced address may represent the status of an external input or an internal program bit
14
Q
What is is another bname for XIC
A
Examine if closed/ Examine-on Contact
15
Q
When is an XIC used
A
When presence of a signal is needed to turn an input on
16
Q
When is the XIC contact true
A
When the addressed memory bit is 1. The external input device is closed and supplies voltage at input terminal
17
Q
When is the XIC contact false
A
When the addressed memory bit is 0. The external input device is opened and does not supply a voltage at the input terminal
18
Q
What are examples of a XIC contacts
A
NO pushbuttons, proximity sensors, and switches
19
Q
What relay contact does the XIC imitate
A
Normally Open
20
Q
What is the symbol for XIC
A
21
Q
What is is another bname for XIO
A
Examine if open/ Examine-off Contact
22
Q
When is an XIO used
A
When absence of a signal is needed to turn an input on
23
Q
What relay contact does the XIO imitate
A
Normally Closed
24
Q
When is the XIO contact true
A
When the addressed memory bit is 0. The external input device is open and does not supply voltage at input terminal
25
When is the XIO contact false
When the addressed memory bit is 1. The external input device is opened and supplies voltage at the input terminal
26
What are examples of a XIO contacts
NC pushbuttons, temperature sensors, limit switches
27
What is the symbol for XIO
28
How does the Energize Output Coil Work
This instruction will only be performed if the condition (input) instructions preceding it provide a path of logical continuity. It tells the CPU to set a bit to 1 or reset a bit to 0 at the memory location specified by the address listed with the symbol
29
What happens when an OTE rung condition is True?
The corresponding field device energizes
30
What happens when an OTE rung condition is False?
The corresponding field device de-energizes
31
What are examples of OTE devices
Lamp, Motor Starters and relay coils
32
When are branching instructions used
If one or more sets of parallel input conditions are required to energize an output device.
33
How does NEG output instruction work
This flips the logic state. The output is energized when the rung is false and deenergized when the rung is true
34
How does the (OTL) latch output work
The symbol represents a retentive output action instruction. When the rung becomes true it tells the CPU to set the bit to a 1 at the memory address specified by the address listed with the symbol. Once the rung consition goes to false, the latch bit remains set
35
When is a latch output used
WHen the device needs to remain on even after the trigerring condition is no longer true
36
What are examples of OTL instructions
Valve, Alarms, Motors
37
How does a Unlatch output instruction work
It us used to reset a latch output(OTL) with the same address. It is the only automatic means for unsetting a latch output.
38
Give a practical example of when the latch and unlatch pair is applicable
Temperature sensor
39
What are the major differences between XIC and XIO
Initially we want it to be open, Initially we want it to be closed
40
What are timers
These are output instructions that are internal ton the programmable logic controller. Threy are capable of producing timed control of devices that they activate and deactivate
41
Give examples of some use cases for timers
playing an action, causing an operation yo run for a predetermined period, recording the total accumulated time of continuous of intermittent events.
42
How is a timer usually activated
Change in logical continuity of its rung.
43
What is the most common controller for a timer
An examine instruction
44
When is the output energised in a rung that has a timer
After the timer has expired
45
Can a timer be reused
Yes, thecontacts for a specific timer can e identified using the stress number
46
What are the information required to program a TImer
Symbol and address, Time Base(1, 0.1, 0.01), Preset Value, Accumulated Value,
47
What are the status bits that are required for the timer
EN, Enable showing that the timer is active, TT, Timer Timing Showing that the timer is currently running, DN, DOme, Showing that the timer has reached its preset
48
When is the enable bit set and reset
It is set when the rung condition in true and resets when the rung condition is false
49
When is the done bit set and reset
When the ACC = PRE
50
How does a Timer on Dely Work
It delays in turning on an output. It begins when the rung becomes true and resets automatically if the rung goes false.
51
How does a Timer-Off-Delay work
It delays in turning off an output. It starts timing when a rung becomes false. When the rung is true, the one bit is enabled and the output is ON. The output stays on during the delay and then turns off after the time is expired.
52
How does Retentive Timer on Delay Work
It is similar to TON. Instead of losing its accumulated vake when the rung condition is false, it is retained.
53
What is a counter
These are output instructions that are internal TP the PLC. A counter counts the number of events that occur and then stores and displays the accumulated value
54
What makes up the sstructure of a counter
Aymbol and address, preset value, accumulated value
55
What are the status bits for a counter
Up counter Enable bit, Down counter Enable bit, Count complete bit, Underflow bit.
56
WHen is a rung counter set and reset
It is set when the rung condition of an up counter is true and resets otherwise
57
Down Counter Enable Bit
Sets a down counter anytime when the rung counter is true
58
When does a count complete bit set
Sets when ACC = PRE
59
When does an overflow bit set
When ACC is greater than maximum count of 32767
60
When does an underflow bit set
When ACC is greater than maximum count of -32767
61
What are the type of counters
Up Counter, eDown Counter, Counter Reset
62
How does a down counter work
It increases by one each time a counted event occurs. The number of events is recorded in ACC. When ACC=PRE, DN is set. CD will email set if counting continues beyond PRE.
63
When is the overflow bit of the up counter set
If the count goes beyond 32,767.
64
How does the Down Counter work.
The instruction decreases by one each time a counted event occurs. The number of events is recorded in the ACC. DN is set untill the ACC value goes below the PRE value.
65
When is the underflow bit of the up counter set
If the count goes below -32,767.
66
Which instruction clears the accumulated value of up and down counters to zero
Counter Reset (RES)
67
What are the advantages of data manipulation instructions
Enable plc to use multibit data to control outputs rather than only one bit. They allow words to be moved within the memory.
68
What are the three categories of data manipulation/handling
data transfer, data conversion, data compare
69
Whatis the role of the data transfer instruction
It is used to move the contents stored in one memory register to another memory location
70
Give examples of data transfer instructions
Move, JMP, clear, masked move
71
What is a Move instruction used for. It is used to move the contents in its source to the specified destination
72
What is a masked move used for
It is used to movedata from a source to a selected portion of the destination.
73
What does the Clear in structuoiin do
Ut sets tehe destination value of a wrdto zero.
74
What does the JMP instruction do
It is used to skip a portion of the ladder program
75
What does data conversion instructions do
enables conversion between binary and equivalent values
76
What is the function of the TOD instruction
It changes a ure 16bit binary number into an equivalent numerical BCD number oin four separate groups of four bits
77
What is the function of the (FRD) instruction
changes four separate groups of BCD values into an equivalent binary value consisting of 16 bits.
78
What does data comparisons instruction do
This instructs the rocessor to compare the numerical contents of two registers to fmake decisions based on their values and the type of instructions used.hese instructuibs are used as input on a rung
79
Give examples of Data comparison instructions l EQU,NEQ, LES, LEQ GRT
80
What format must the source and destination of a comparison be
Source must be a word address, destination can be a program constant or a word address.
81
What are the parts of a typical mathematical instructuction
Source A, Source B and Destination
