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Test 2 PLC
Terms in this set (60)
The wiring diagrams show the circuit in its simplest form.
The ladder diagram, also referred to as a schematic or elementary diagram, is used by the electrician or technician to speed their understanding of how a circuit works.
Devices or components are shown in order of importance whenever possible in a ladder diagram.
Logic gates can be combined to create very complicated control logic.
By combining two NOT gates and an AND gate, we get a NAND gate.
The ____________________ shows the circuit wiring and its associated devices in their relative physical location.
The vertical power lines (rails) of the ladder diagram represent the ____________________ of the circuit.
Voltage potential or Voltage or Potential
Electrical devices or components are shown in their ____________________ condition on a ladder diagram.
The ____________________ has been the "working language" of electricians and electrical engineers for many years.
The NOT gate is often referred to as a(n) ____________________.
Ladder logic is a good choice for a programming language because it closely resembles the way circuits are hard-wired.
The EXAMINE OFF instruction is only logically true when the device referenced is ON, or open.
When the N.C. symbol is programmed in a ladder diagram, any address that is actually ON becomes logically true and power can flow.
The number of times an input device can be addressed and used in a programmed circuit is limited to eight.
There are many more applications and circuits that normally require two- or three-pole devices that now only require single-pole devices when programmed for a PLC.
A PLC is normally programmed using a(n) ___________________ logic-type language.
___________________ contacts in a motor control circuit control the path for current flow to the output.
Because the processor views the N.O. contact instruction as a request to examine a given address for an ON condition, it is referred to as a(n) ___________________ instruction.
Whenever the processor sees an N.O. contact in the user program, it views the contact symbol as a request to examine the address of the contact for a(n) ___________________ condition.
When the N.C. symbol is programmed in a ladder diagram, the processor views it as a request to examine the address of the contact for a(n) ___________________ condition.
To prevent unauthorized On-Line programming, a key switch is provided, either on the programming device or on the processor, to restrict the access to a monitor-only mode, or to Off-Line and monitor-only mode.
Once a program is complete, it should be tested while still in the Off-Line mode.
The function or functions of the processor that can be locked out with the key switch or by using passwords are fairly standard and are the same from PLC to PLC.
Most PLCs are designed so that any input contact (N.O. or N.C.) or output coil can be Forced On or Off.
With a ControlLogix 1756-L62 processor, controllers can be placed in any slot, but it is not possible to place multiple controllers in the same chassis.
When programming using a personal computer and specialized software, a(n) ____________________ may be used to limit the access to the processor program.
____________________ programming means that the program is being developed without being connected to the process or driven equipment.
The Output symbol with a (?) indicates that the symbol needs a(n) ____________________.
The RSLogix software gives a(n) ____________________—Use a Larger Power Supply warning when the mix of I/O requires a larger power supply than has been selected.
When entering addresses, the ____________________ can be used instead of the colon (:).
A network constitutes one rung of a ladder diagram that starts at the right rail and ends at the left rail.
The easiest way to avoid nesting is to remember that all branches must start at a common point, and all of the branches must end at the same location.
The way the processor scans the program is the same from PLC to PLC.
It is common practice to wire the overload contacts to an input module.
When a hard-wired backup control circuit is used in conjunction with a PLC to control a motor, then the overload contact on the motor starter must be wired in series with the motor coil to provide protection for the motor under both means of control, PLC and hard-wired.
A(n) ____________________ is defined as a group of connected logic elements used to perform a specific function.
A typical PLC network limitation is ____________________ series contacts per line.
With a parallel output configuration, all of the outputs are ON or OFF at the same time, based on the ____________________.
A branch circuit within a branch circuit is known as ____________________.
As a general rule, all input devices, except STOP buttons, are wired ____________________.
MCRs are often used with circuits that have off-delay timers so the circuit can be shut down completely without waiting for the timers to time out.
An MCR zone can be nested within another MCR zone.
The jump instruction (JMP) tells the processor to jump over a portion of the program.
Jumping backward does not add to the total scan time.
The one-shot instruction (ONS) is an input instruction that makes the rung true for just one program scan, based on a false-to-true transition of the instruction that precedes the one-shot instruction.
In standard relay control systems, a(n) ____________________ control is often used to control power to the entire circuit or just to selected rungs.
MCRs are sometimes called Master Control ____________________ because they reset the output to zero or OFF.
____________________ instructions will remain ON, or true, even when the MCR instruction is false.
When an MCR instruction has been programmed with no logic element preceding the instruction, it is said to be programmed _____________________.
The ____________________ is also used when debugging a new or modified program.
With the ON delay timer, the delay in contact operation begins before the timer coil has been energized, or turned ON.
The basic pneumatic timing relay is designed so that additional instantaneous contacts may be added.
When a timer uses the format used by the Allen-Bradley timer, the preset time can be programmed with any value from 0 to 16,000.
The retentive timer lets the timer START and STOP without resetting the accumulated value to 0.
When circuit requirements demand more time than is available from a single timer, two or more timers can be programmed together.
To avoid confusion when reading electrical drawings with OFF delay contacts, it must be remembered that normal refers to the coil ____________________ it has been deenergized.
In an RTO, bit 13 is known as the ____________________ bit.
Retentive timers (RTO) can be programmed to replace ____________________ timers.
A common problem in programs that have ____________________ timers is that the timer is not accumulating time, even though the timer rung is true.
Programming two or more timers together to extend the timing range is called ____________________.
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