Programmable Logic Controllers Flashcards
PLC stuff
1
Q
Sectors that PLCs are used include (5 items)
A
1: Chemical/petrochemical
2: Auto manufacturing
3: Metal smelting/mining
4: Lumber/pulp/paper
5: Food/beverage production
2
Q
Smaller PLCs are hardly more than _____.
A
Smart relays.
3
Q
Large PLCs may have over.120 000 IO points. T or F.
A
True.
4
Q
Three items that control systems consist of are:
A
1: Input devices
2: Controller
3: Output devices
5
Q
Three examples of input devices are:
A
Switches, limits, thermostats.
6
Q
A controller can receive input info in what two ways?
A
Hard wired circuit or software program.
7
Q
Three examples of output devices are:
A
1: Relays
2: Contactors
3: Solenoids
8
Q
Output devices control devices such as: (5 items)
A
1: Motors
2: Pumps
3: Heaters
4: Fans
5: Valves
9
Q
PLCs are able to perform their own _____
A
Internal diagnostics
10
Q
Four advantages of PLCs over relay control are:
A
1: Lower cost
2: Programmability
3: Reliability
4: Expandability
11
Q
Troubleshooting on a PLC system is _____ and reduces _____.
A
Easier
Down-time
12
Q
PLCs are physically smaller than _____ with smaller _____ requirements.
A
Control panels with numerous relays
Energy
13
Q
Does hard wiring need to be changed to re-program or update PLC software?
A
No
14
Q
A program is usually _____.
A
Ladder logic
15
Q
A program graphically displays _____ as well as _____.
A
Status of devices
Power flow in program
16
Q
Ambient conditions that some PLCs are designed to withstand are:
A
Excessive heat, humidity, exposure to mechanical damage (vibration).
17
Q
Static electronic switching means _____.
A
No moving parts.
18
Q
Two ways to expand PLC systems are:
A
1: New modules plug into existing PLC
2: Add another PLC and link/group with communication data highway
19
Q
Communication data highway is a means of _____.
A
Connecting multiple PLCs in a system.
20
Q
Discreet input devices are _____ (3 items) that are either off or on.
A
1: Switches
2: Relay contacts
3: Sensors
21
Q
Discreet output devices such as _____ (4 items) respond to either being energized or de-energized.
A
1: Pilot lights
2: Contactor coils
3: Relay coils
4: Solenoids
22
Q
Discreet input and output devices require _____.
A
Power from a separate source.
23
Q
Optoisolating is how _____ is achieved between the discreet IO circuits and the internal circuitry of the processor module.
A
Electrical Isolation.
24
Q
Analogue devices are either on or off. T or F.
A
F. They operate over a range of voltage or current.
25
A solid state electronic switch for DC would be a _____.
Transistor
26
A solid state switch for AC is a _____.
Triac
27
An interposing relay does what function?
Relay coil that can handle higher current and is operated by the solid state switch.
28
Some examples.of measured values are:
Temperature, pressure, speed, position.
29
The most common analog current standard is _____.
4 mA - 20 mA
30
Minimum signal for 4-20 mA analog is 4 mA because _____.
Allows PLC to tell difference between 0% signal and broken wire connector.
31
Proportional control is gained using an analog output card for processes such as a _____.
VFD motor speed controller.
32
A shield in STP cable is also called a _____.
Drain
33
STP cable means _____.
Shielded twisted pair
34
The drain is usually grounded at only one end, usually _____.
In the PLC panel.
35
PLC programming evolved from _____.
Boolean algebra programs
36
Three graphic based languages used for PLC programming are:
1: Ladder diagrams
2: Function block diagrams
3: Sequential functions/flow chart
37
Two text based languages for PLC programming are:
1: Structured text
2: Instruction lists
38
The most common programming language is _____.
Ladder diagram
39
The numbers used above symbols in a ladder diagram represent _____.
Input/output terminal address
40
Each function block may have several inputs and _____.
Settable parameters
41
Function blocks can be thought of as _____.
Small programs within a main program.
42
Function block diagrams are commonly used in _____.
Europe
43
Sequential Function Charts are used for large process controls and can involve _____.
Logic or several LD or FBD.
44
Text based programs were once commonly used with _____.
Hand held programmers
45
Structured Text is similar to what computer programming language?
Basic
46
Instructiom Lists are similar to _____.
Assembler language programs
47
Instruction Lists are more like the machine code used to make a _____ function than a process to be controlled.
Microchip
48
Four major hardware components of a modular PLC are:
1: Power Supply
2: Backplane
3: Processor (CPU)
4: IO modules (input/output
49
The power supplied to a PLC is clean, filtered/regulated and provides _____.
Protection to system components
50
Does a PLC supply any of the field IO devices?
No
51
Field IO devices are _____ from the backplane, CPU and power supply.
Isolated electrically
52
The means for a PLC to communicate with other components and distribute power for internal operations is done through _____.
A backplane
53
A backplane is a _____
Power and communications bus
54
What is another name for a complete unit PLC?
Shoebox PLC
55
Shoebox unit PLCs often replace _____.
Small relay systems.
56
What does a processor do?
Executes user programs and communicates with other devices.
57
What does STP stand for?
Shielded twisted pair
58
What is the sequence of carrying out processor functions called?
Processor scan
59
What type of memory is used in PLCs?
RAM, ROM, EEPROM.
60
What happens if volatile memory loses its electrical power source?
Memory cleared of all data
61
What is required for volatile memory to keep stored data and programs when power is removed?
Battery backup
62
Non-volatile memory is considered _____.
Permanent.
63
Is RAM a volatile memory or non volatile?
Most is volatile. Non volatile has self contained battery within package of memory chip.
64
ROM is volatile or non volatile?
Non volatile
65
ROM info may be altered or written to by a user, true or false?
False
66
What does RAM mean?
Random Access Memory
67
What does ROM mean?
Read Only Memory
68
What does EEPROM mean?
Electrically erasable programmable memory
69
EEPROM is integrated circuit memory considered to be (volatile, non volatile?)
Non volatile
70
An example of EEPROM is _____.
Flash memory cards/USB drive
71
What are some switches that may be used as a sensing device?
Pressure, temperature, or mechanical limit switches with an on/off signal
72
Analogue sensing devices would have signals of changing levels of _____ or _____.
Voltage, current.
73
7 control functions that special IO modules are used for:
1: Position control
2: High speed counters
3. Temperature controls
4: Proportional integral derivative control (PID)
5: Fuzzy logic control
6: Identification sensors cam positoners
7: Analogue IO
74
How many cables would be between a remote IO and a PLC?
1
75
What is a data highway?
LAN cabling that connects a number of PLCs (and PCs) to exchange programs/data
76
What is the most common analogue voltage standard?
0 - 10 V DC
77
PLCs are actually an _____ _____ with specially designed hardware and software.
Industrial computer
78
"Hardware" in PLCs refers to _____. (3 items)
Mechanical, electrical, and electronic components.
79
What are the four basic components of an Automated Control System?
1: PLC
2: Input devices
3: Output devices
4: AC circuits
80
CPU power supply, input devices and output devices all need their own _____.
Separate AC supply.
81
Lights, coils, solenoids, magnetic starters and meters are examples of _____.
Output devices
82
Is the programming device required when the program is running?
No, except to monitor the program.
83
A desktop computer, laptop or hand held programmer are examples of _____
Programming device.
84
Desktop computers, laptops and handheld programmers are also called _____.
HMI, Human Machine Interface
85
The power supply of a CompactLogix controller is located where in the module?
Anywhere in the 2nd to Fourth position.
86
The power supply of a CompactLogix controller is located where in the module?
Anywhere in the 2nd to Fourth position.
87
What is the maximum position for the IO modules in a CompactLogix?
12
88
In a single bank CompactLogix system, you cannot place more than _____ between the power supply and end cap, making a maximum of _____ modules.
8 I/O modules, 11
89
Data is _____ (received) by a processor and _____ (sent) to other PLC components
Read, write
90
A processor module has _____ ports and _____ for a _____.
Two communication, one slot, memory card.
91
The power supply will be sized to accomodate the load of _____.
All of the cards in the assembly.
92
Input/Output modules provide an _____ between the processor and the _____.
Interface, discreet field device
93
Analogue modules provide an _____ between the processor and the _____.
Analogue IO field devices.
94
Endplates complete the assembly, with the leftmost housing _____ and the rightmost housing _____.
Battery for the EEprom
Terminal assembly to terminate backplane.
95
Can a programming device both read and write to a PLC processor?
Yes
96
What provides housing for the modules?
A chassis or separate enclosure.
97
What does a power supply do?
Converts AC or DC voltage to specified value with required VA capacity to operate electronic equipment
98
The power supply is considered the first line of _____.
System reliability and integrity.
99
PLC power supplies are designed to operate under constant frequency and voltage only. T or F.
False. Designed for wide range of fluctuations that may occur in a large system.
100
If the supply frequency fluctuates more than the specified values, what will the PLC do?
Shut down the processor.
101
What is EMI?
Electromagnetic interference
102
Where would a power supply need to be shielded?
Areas where EMI is generated
103
Power supplies are selected according to _____.
The current requirements of the modules
104
What are two ways to provide power to the field IO devices?
External source or auxillary control transformer
105
What does Line Signal Conditioning do?
Purifies AC sine wave to eliminate voltage surges, current spines, or other incoming electrical noise.
106
Five duties of the power supply module are:
1: Line Signal Conditioning
2: Step down voltage
3: Rectifier converts AC to DC
4: Filter smooths DC to fairly constant, negligible ripple
5: Voltage Regulator provides steady output to components
107
Where is the power supply of the CompactLogix mounted in this lab? What are its output current ratings?
Immediate right of the processor.
4A at 5V DC and 2A at 24V DC
108
What system activities do a processor govern?
Receiving, analyzing, processing and transmitting data.
109
What are two other terms for processor?
CPU, microprocessor
110
The CPU is the _____ of the system.
Intelligence
111
The CPU and memory _____ to execute the _____ (+4 items).
Work together
Operating system, interpret/execute user programs, communicate with devices, perform other housekeeping.
112
Primary function of PLC processor that is also called Processor Scan:
Read/store status of all input devices, execute user program by solving ladder logic, update status of outputs.
113
What are the five steps of a processor scan? Which step is the longest?
1: Input scan
2: Program scan
3: Output scan
4: Service communications
5: Housekeeping/overhead
Program scan is the longest time interval.
114
A Watch Dog timer is part of what area of the system? What does it do?
Internal diagnostic system.
Shuts down processor and creates fault code if time out error occurs.
115
Is it dangerous to edit online when a controller key switch is on the RUN position?
Yes
116
Will the controller execute tasks while keyswitch is in PROG position?
No
117
Can you edit online in run mode of the REM keyswitch position?
Yes
118
Does battery backup continue running the processor during a power outage?
No. Only keeps programming intact.
119
Primary function of a processor is:
Read inputs, solve ladder logic, and update outputs
120
Which modules are used to electrically isolate the processor from the field devices?
I/O modules
121
Status indication on IO modules helps with _____.
Faster system analysis
122
Input modules take signals from devices and converts to a _____ _____ usable by the processor.
Voltage level
123
Sensing devices can be things such as: (5 items)
1: Switches
2: Photo-eyes
3: Proximity switches
4: Limit switches
5: Pressure transducers
124
What is Opto-isolator?
Small relays/filter circuitry.
125
What does optoisolating protect the processor from?
Voltage transients and magnetic interference.
126
Output modules send information to an output field device via _____ _____.
Electrical interface.
127
Are output modules equipped with surge protection and/or fusing?
No.
128
What kind of protection is usually used for inductive loads?
Surge suppresion
129
A loading resistor connected in parallel with a load will have what effect?
Limit the effects of leakage current through solid state outputs.
130
What size resistor would be used for a loading resistor at 120 VAC? And for 240 VAC?
120: 15 kiloohm, 2 watt
240: 15 kiloohm, 5 watt
131
What will develop over an unloaded output?
Hazardous condition.
132
Discreet IO modules are available in _, __, or __ points per module.
8, 16, 32
133
What are the AC ratings of digital AC input modules?
24, 120, 240
134
What are the DC ratings of digital AC input modules?
5(TTL), 24, 48
135
What are the AC and DC ratings of digital AC output modules?
120/240, 24VDC, 5 VDC(TTL)
136
What is the current rating of digital AC output modules?
0.5 A - 2 A per output point
137
What can a relay output of a digital DC combination module control?
5-265 VAC, 5-125 VDC, loads up to 2.5 A per point to a max of 20 A per card.
138
What would the voltage be at 75% of the signal?
7.5 VDC
139
What would the current be at 25% of the signal?
8 mA
140
What would the voltage be if the current were 12 mA?
5 VDC
141
What percentage of signal is 16 mA? What would the voltage be?
75%
7.5 VDC
142
What would the current be at 0% signal and 0 VDC?
4 mA
143
Special purpose modules for specialized needs could include applications such as:
Motion Control
Video Recognition module
ASCII module
High speed counter modules
Servo positioning module
Compact IO to PowerFlex drives
Thermocouple (mV) signals
Resistance temperature detector (RTD) input module
144
What causes voltage transients?
Contact bounce and electrical noise
145
Only some input modules use input filtering. T or F.
False.
146
Analogue signals are typically interpreted as _____ _____ by the PLC
Integer value
147
What are four items represented by analog signals?
Pressure, temperature, flow, weight.
148
PLCs typically use __-bit signed binary processors.
16
149
Analog signals use voltage or current with a _____ _____ to the process signal.
Proportional magnitude
150
When might you want to use additional surge suppresion? (4 items)
Inductive loads such as relays, magnetic starters, solenoids and low VA motors
151
Electrical isolation between processor and IO module is achieved by optical isolation as well as _____.
Small relays in the IO modules
152
What is peripheral equipment?
Accessory or auxiliary to a central system
153
What are some methods to input a program to a PLC processor?
1: PC or laptop with software
2: Operator Interface Devices
3: Modems
4: Printers
5: Alphanumeric displays
6: Communication devices
7: Memory device
154
What is memory in a PLC?
A two dimensional array of storage cell, each cell storing a single bit of information.
155
What values represent a bit of information?
A 0 or a 1.
156
Binary data is stored in memory by a process called _____.
Write
157
Binary data is retrieved from the memory by a process called _____.
Read
158
Data storage locations, each identified by an address, is called _____.
Memory
159
What is BIT an acronym for?
BInary digiT
160
What are the 1s and 0s of binary representative of?
Presence or absence of voltage at that particular location.
161
If a bit's status is 1, is it considered ON (set) or OFF (reset)?
ON
162
If a bit's status is 0, is it considered ON (set) or OFF (reset)?
OFF
163
When might you group bits for transferring?
Transferring numbers from a thumbwheel to digital readout or PLC.
164
What is a byte?
A group of bits (the smallest value that can be handled simultaneously by the processor).
165
What is a typical byte size?
8 bits
166
What is a "word"?
Grouping/number of bits in a sequence treated as a unit.
167
What is the word length of the CompactLogix PLC?
32 bits
168
What is a memory flash card?
RAM memory module that can insert directly innto PLC processor.
169
All PLCs must have memory allocated for _____ (4 items).
1: Executive programs
2: Processor work area / Scratch pad
3: Data area
4: User program area
170
Which two items are not accessible to users and are part of the System Memory?
Executive and Scratch Pad
171
System Memory could be described as equivalent to _____.
BIOS of a pc
172
Executive memory is considered to be _____.
Permanent
173
Scratch pad memory is considered ______ storage.
Temporary
174
Which two items are accessible to the user?
Data Area and User Program
175
Data Area and User Program can be described as _____.
Application memory
176
Max memory size specified by the manufacturer will usually only include the _____.
Application memory
177
What are the two basic items that memory stores?
State of input/outputs (Data area)
Program that controls the outputs (User program)
178
A "tag" can refer to a _____ location or a structure location that is _____ in size.
Single bit
Multiple words
179
What are the three properties assigned to a tag?
Type, Scope and Data Type
180
What are the four types of tags?
1: Base tags
2: Alias tags
3: Produced tags
4: Consumed tags
181
All data stored in four byte groupings in 32 bits of consecutive data is called _____ tag.
Base
182
Alias tags refer to memory that is defined by _____.
Another existing tag
183
Four ways that Alias tags can be used are:
1: Programming ladder
2: Assigning descriptive name to IO device
3: More simple name to complex tags
4: Descriptive name for element of an array
184
Produced tags and Consumed tags are used when _____ and are always ______.
Information needs to be shared between controllers
Controller scoped tags
185
Program Scope tags can be accessed by all routines in the controller. T or F.
False
186
Controller Scope tags are accessible only by the parent program. T or F.
False
187
What type of languages are most commonly used with PLCs?
Graphic based
188
How many words of Data Table memory do counters and timers require? What are they?
Three - Accumulated, Preset, Address
189
What is the max time that can be programmed in a TON instruction?
596. 523 hrs
35791. 394 min
2147483. 647 s
190
When an output bit is "1", it's corresponding output terminal is "off". T or F
False
191
What does the accumulated value in a CTD need to be to turn off the .DN bit?
Below the preset value
192
Data types may be ______ or ______.
Atomic or structured
193
Five atomic data types are:
1: Bool (single bit of a 32 bit word)
2: Sint (short integer, 8 bits [1 byte] of a 32 byte word)
3: Int (integer, 16 bit group of 32 bit word)
4: Dint (double integer, 32 bit word)
5: Real (32 bits, includes decimal, used for math/analog process conrol.)
194
What are the three kinds of strutures?
1: Module Defined Structures
2: Predefined structures
3: User Defined Structures
195
Data, status and fault information is contained in which structure?
Module Defined Structures.
196
Control, counter, and timer structures are found in which structure?
Predefined Structures
197
Name, data type, style and radix are required by which structure?
User Defined Structures
198
An array lets you group data under a common name as long as what condition is met?
They are of the same type
199
Which part of C5[0] is the subscript?
0
200
How many dimensions can an array have? What is the benefit of this?
As many as three. Flexibility for 1-3 subscripts.
201
Three dimensional arrays are generally only used with ______ ______ programs
Motion control
202
What is a reason for using arrays?
When upgrading from a different model.
203
The data area of the CompactLogix PLC data area contains what?
Tags
204
A basic unit of logic is called a _____.
Routine
205
What types of logic can be used in a routine?
Ladder, function block, sequential function chart, structured text.
206
What language would you use for machine interlocking and operations that may need to have maintenance personnel troubleshoot?
Ladder logic
207
What language would you use for continuous process, drive control, and loop control?
Function block diagram
208
High level management of multiple operations would be coded using which language?
Sequential function chart
209
Complex mathematical operations, ASCII string handling, and specialized arrays would be coded using which language?
Structured text.
210
A program contains every _____.
Routine
211
JSR instruction means:
Jump to Subroutine
212
If you do not want a program to run, where in the controller organizer should it be stored?
Unscheduled programs folder.
213
Does a task define when a program will execute?
Yes
214
Up to __ tasks can be configured in the controller.
6
215
A watchdog will trigger a _____ if the task runs too long.
Fault
216
Can you use 5 continuous tasks in a project?
No. Can only use 1.
217
What is the max periodic tasks that are able to be used in a project?
6
218
The time period of a periodic task can be configured from 1 ms to ____ s.
2000
219
The default time period in a periodic task is __ ms.
10
220
What are the position numbers of a PLC assembly?
1-5
221
What are the slot numbers of a PL assembly? Which module goes in slot 0?
0-7. CPU/Processor
222
If the location of the IO module is on the main DIN rail, what is the location part of the address?
LOCAL
223
Describe the address LOCAL:2:I.DATA.0
LOCAL: location is on main DIN rail. "Adapter type and name" would be used if IO module is remote.
2: Slot number of the module being referenced.
I: Module type. I=Input O=Output
DATA: Discreet IO. Use "Channel #" for analog
0: Bit number from 0-15
224
What does XIC mean?
Examine if closed
225
What does XIO mean?
Examine if opened
226
When an instruction becomes true, that means that it has been _____.
Energized
227
When an input terminal is energized, it's corresponding bit is __.
1
228
When an input terminal is de-energized, it's corresponding bit is __.
0
229
What does the input module do before storing the result in the input tag data area?
Filters, isolates the incoming signal and changes it to 5 VDC
230
Is electrical isolation required between the internal 5 VDC of the output module to the actual operating voltage of the lamp?
Yes
231
Each word in the IO tags corresponds to what?
A specific slot within a certain chassis.
232
Are timers input or output instructions?
Output
233
Is there additional hardware needed for timers?
No. It is in the software.
234
The minimum timer setting of a PLC timer an be as low as __ ms.
1
235
All timers require how many words of memory in the timer area of the data table?
Three
236
What does Mnemonic refer to?
The 'label' given to a specific bit.
237
The three different types of timers are:
1: Timer On Delay
2: Timer Off Delay
3: Retentive Timer On (RTO)
238
An integral part of most control systems are _____.
Timers
239
What are five uses of timers?
1: Delay starting cycles
2: Control intervals
3: Repeat cycles
4: Flashers
5: Provide automatic resets
240
A TON instruction begins accumulating time when the run goes _____.
True
241
A TON instruction will be true until what happens?
The rung goes false or,
The accumulated value = preset value or,
A reset (RES) instrution, if added, is energized
242
DINT refers to "double integer", meaning what?
An actual number
243
TIMER is a _____ structure.
Predefined
244
TIME BASE is __ seconds.
0.001
245
PRESET is the value which the timer must reach for the processor to do what?
Set the done bit (.DN)
246
The ACCUMULATED VALUE is the number of _____ the instruction has counted.
Time increments
247
How many status bits do timers have?
3
248
Status bits are entered in _____.
Mnemonics
249
(BOOL), or 'Boolean' means only 'high' and 'set'. T or F
False.
High or low, set or reset, etc.
250
In a TON, the TT bit is set when the rung goes _____ and remains set until _____.
True
Until ACCUMULATED = PRESET
251
In a TON, the DN bit is set until:
The rung goes false
A reset instruction resets the timer.
252
If a power failure or other circumstance interrupts the TON before the PRESET value is reached, what happens?
Timer enable remains set, TT remains set, ACCU remains the same.
253
The timer is in the __ area of the tag base?
T4
254
How many timer structures can each timer tag base contain?
Limited only by memory
255
The time PRESET has a range of 0 - _____.
2,147,483,647
256
A TOF instruction begins accumulating time when the rung goes _____.
False
257
A TOF instruction will continue timing until what occurs?
The ACCU=PRESET
The rung goes true
258
Can you use a RES with a TOF?
No
259
If the rung goes true before the timer of a TOF has not timed out, will the accumulated value reset?
Yes
260
In a TOF, the EN bit is set when the rung goes _____.
True
261
In a TOF, the TT bit is set when the rung goes _____ and the ACCU value is _____.
False
Less than the PRESET value
262
The TT bit of a TOF is reset when:
The rung goes true
The DN bit is reset
ACCU=PRESET
263
The DN bit of a TOF is set when the rung goes _____.
True
264
The DN bit of a TOF is reset when the ACCU is ______ the PRESET.
Equal to
265
What needs to happen for the ACCU value of an RTO to reset?
Rung goes false, program mode, or power loss to the processor.
266
When the processor resumes operation or the rung goes true, what value will an RTO that was de-energized with an ACCU value of 10s resume timing from?
10s
267
How do you reset an RTO accumulated value?
A RES with the same addres in another rung.
268
An RTO's .EN bit is set when _____.
The rung goes true
269
An RTO timing bit will be set when _____.
The rung goes true
270
The .DN bit of an RTO timer is set when _____.
The ACCU=PRESET
271
Can you use a RES instruction with a TOF?
No
272
Why must you not use a RES instruction with a TOF?
May cause unpredictable operation that may result in injuries of personel.
273
RTOs are in the __ area of the tag base.
T4
274
Is a counter an output or input instruction?
Output
275
Counters in PLCs provide the same functions as mechanical counters. T or F
True
276
Counters only activate a device after reaching the preset value. T or F
False. Activates or deactivates
277
Counter instructions are _____ outputs.
Internal
278
Is additional hardware needed for PLC counters?
No
279
What three words do counters require?
Control word
Preset register word
Accumulator register
280
What are the three types of counters and their mnemonics?
Count Up = CTU
Count down = CTD
High Speed Counter = HSC
281
What are five industrial applications for counters?
1: Packaging
2: Product tracking
3: Measuring lengths/speed
4: Keeping track of inventory
5: Reporting
282
What is the range of a counter in ms?
-2,147,483,648 to +2,147,483,647
283
The ACCU value of a counter will reset if the instruction is de-energized and then re-energized. T or F
False. Must have a reset.
284
The PRESET value of a counter is a ___-bit integer value
32
285
The accumulated value of a counter stops incrementing once the .DN bit is set. T or F
False
286
A counter with an OV bit wil do what once the limit has been reached?
Wrap around and begin counting from the lower limit.
287
What is the upper programmable limit in ms?
2,147,483,647 ms
288
What is the programmable limit in minutes?
35,791.394
289
What is the programmable limit in hours?
596.523
290
CTUs and CTDs are in the _____ area of the tag base
C5
291
Overflow bits are set when ______.
ACCU exceeds PRESET
292
Should you use a negative preset value in a counter if also using a RES instruction?
No
293
If a negative preset is used and a RES instruction is executed, what will happen?
Resets the .DN bit, and prevents the counter instruction from operating.
294
What are the most common ways of transmitting analog signals?
Proportional voltage or current signals
295
What are 4 common DC voltages?
0-5 Vdc
0-10 Vdc
2-10 Vdc
±10 Vdc
296
Transmittors and sensors are not analog devices. T or F
False.
297
Temperature, speed, flow, weight and pressure are all analog devices. T or F
True
298
How many input and output channels do the CompactLogix analog IO modules have?
4 input, 2 output.
299
4-20 mA is an analog signal that can be converted by the CompactLogix analog input module. T or F.
True
300
Two methods of wiring analog IO modules are _____ and _____.
Single ended
Differential
301
Are all inputs tied to a common ground using the single ended wiring method?
Yes
302
Which wiring method isolates the channels from one another?
Differential
303
What 5 things may cause errors in a measurement process?
1: Electrostatic fields
2: Inductive pickup
3: Radio frequency interference
4: Power line noise
5: Ground loop current
304
What causes ground loop current?
Poor ground connection
Differing common mode voltages in the system
305
Smaller systems are more likely to have ground loop issues. T or F
False. Large systems would.
306
What are two ways to prevent ground loop current?
Proper grounding
Equipment with floating measurement
Same ground reference
