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100 Cards in this Set
- Front
- Back
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How do you identify a directional control valve? |
Number of spool positions, number of solenoids, and type of operation. |
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What are the three purposes of a relay? |
To deliver, remove, and hold power. |
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What are memory bits like? |
Relays |
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What are inputs used as? |
A condition |
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What do outputs relate to |
The physical world |
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Do memory bits relate to the physical world? |
No. |
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What is position indication needed for? |
It is needed for feedback |
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What do sensors do? |
Provide feedback to the PLC and let the machine know the current state of its operation |
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What do sensors do for the controller? |
Give it information so it can make a decision. |
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What do sensors do in general? |
Give feedback. |
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What does a limit switch require? |
Physical contact to operate |
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Are limit switches solid state? |
No |
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Is this PNP or NPN? |
NPN. It's switching the neutral. |
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Is this PNP or NPN? |
PNP. It's switching the positive. |
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If the load is already connected to neutral, is the sensor PNP or NPN? |
PNP. |
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What is the input module in relation to the input? |
The load. |
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Is this sinking or sourcing? |
Sourcing. PNP. |
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Is this sinking or sourcing? |
Sinking. NPN. |
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What are field devices? |
Sensors. |
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What does a field device on a positive side equal? |
Sourcing. |
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What does a field device on a negative side equal? |
Sinking. |
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What does a sourcing field device connect to? |
A sinking I/O card. |
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What does a sinking field device connect to? |
A sourcing I/O card. |
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If the common is positive, is it NPN or PNP? |
NPN. |
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If the common is negative, what does that equal? |
PNP. |
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What do addresses do? |
Direct the data file type to a specific point in memory. |
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What is the letter I used for in addressing? |
Inputs. |
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What is O used for in addressing? |
Outputs. |
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What is is B used for in addressing? |
Internal memory addressing. Dummy bit. |
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What is T used for in addressing? |
Internal memory for a timer. |
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What is C used for in addressing? |
Internal memory for a counter. |
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What does B stand for? |
Binary. |
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What is O0? |
Output. |
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What is I1? |
Input. |
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What is S2? |
Status. |
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What is B3? |
Bit |
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What is T4? |
Timer. |
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What is C5? |
Counter. |
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What is R6? |
Control |
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What is N7? |
Integer |
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What is F8? |
Floating point. |
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What does Status do? |
Stores controller operation information for troubleshooting. |
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What are bits? |
They store internal relay logic. |
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What does controller do? |
Stores length, pointer position, and status bit for controller instruction such as shift registers. |
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What are integers? |
They store bit information or numeric valves. |
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What is the range of integers in PLCs? |
-32767 to 32768 |
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What is the purpose of programming a PLC? |
To control the state of the PLC outputs based on current condition of PLC inputs |
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What is the most popular type of PLC language? |
Ladder logic. |
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What does PLC logic purposely resemble? |
Relay logic. |
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How are rack/group or rack/slot systems organized? |
The programmer assigns the data from an input field device to an input instruction |
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How are tag based systems organized? |
Variable names for program values are not tied to specific memory locations in the memory structure? |
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What are rack/group or rack/slot systems used in? |
Older Allen Bradley PLCs and micro PLCs. |
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What are tag based systems used in? |
Newer Allen Bradley PLCs. |
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What does PLC stand for? |
Programmable logic controllers. |
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What are PLCs defined as? Not what it stands for. |
Special purpose industrial computers designed for use in the control of a wide variety of manufacturing machines and systems. |
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Is there only one type of PLC? |
No, there are many brands, but they all do the same. |
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Where are PLCs used in? |
Many many industries. |
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What are PLCs replacements for, and why? |
Relay logic, and because they are more cost effective. |
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Do you have to change the wiring to change the operation of the PLC? |
No. Just change the programming. |
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What are PLCs? |
Computers designed to operate in harsh physical and electrically noisy environments that are present in production plants. |
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Are relays easy to interface with other devices, and dependable? |
Yes. |
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What are PLCs sometimes known as? |
Industrial workhorses. |
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Is ladder logic easy to troubleshoot? |
Yes. That's a big part of it. |
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Who created PLCs? |
Dick Morley. |
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When were PLCs first thought of? |
1968. |
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When were PLCs first introduced? |
1970. |
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Where were PLCs first installed? |
The Oldsmobile division of General Motors Corporation. |
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What happened to PLCs in the mid 1970s? |
Communication capabilities began to appear. |
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What happened to PLCs in the mid 1980s? |
PLCs became smaller and they became programmable by PCs. |
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What happened to PLCs in the 1990s? |
Standardizations and introduction of sub-standards like control net, device net, etc. |
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What happened to PLCs in the 2000s? |
Ethernet was introduced. |
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What does the future hold for PLCs? |
It is limitless. |
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What is the definition of field devices? |
External devices that measure conditions in the production area. |
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What are the three main parts of a PLC? |
The backplane, the processor, and the power supply. |
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What does the backplane provide? |
Power and data interface for modules. |
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What do the copper conductors on the backplane do? |
Provide a databus. |
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What do keying bands do on the backplane? |
Prevent integration of a module or connection into the wrong location or slot. |
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What is the processor? |
The CPU. |
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What does the CPU do? |
Handles all logical operations and performs math computations. |
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What does the processor contain? |
All RAM, ROM, and CPU. |
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In older systems, where does the processor have to be? |
In slot zero. |
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What are power supplies? |
Fused. |
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What do power supplies have? |
A plug in for battery back up. |
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What does the power supply provide? |
The power to the processor and the modules plugged into the backplane. |
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What are some other parts on PLCs? |
Rack, and swing arms. |
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What is the rack of the PLC? |
Provides mechanical support for the backplane and electrical connections. |
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What are the swing arms of the PLC? |
They provide control wiring termination for field devices. |
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On swing arms, how many points does the terminal strip have? |
Ten. |
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How many points does the input terminal strip have on the swing arm? |
20. 16 for inputs, 4 for COM power. |
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How many points does the output terminal strip have on the swing arm? |
36 points. 16 for outputs, 17 for COM power, and 3 not used. |
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What is a circuit that has this symbol in it? |
An opto-isolator circuit. |
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What are the PLC types? |
Micro and modular. |
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Which is fixed and which is adjustable out of micro and modular PLCs? |
Micro is fixes and modular is adjustable. |
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Do micro PLCs use a rack? |
No. |
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Do modular PLCs use a rack? |
Yes. |
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What are the types of modules? |
Analog, discrete, thermocouple, bar code readers, stepper motor, and servo modules. |
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What are the four functions of the I/O modules? |
Indication, termination, isolation, and signal conditioning. |
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What dies a rectifier do? |
Concert AC to DC. |
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What do optoisolators do? |
Isolate the input module from the CPU and drops the DC level. |
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What is a condition? |
Something in a circuit that satisfies an output. |
