Test #8 Flashcards
(31 cards)
Define sequential process
Sequential process consist of a sequence of one or more operations that must be performed in a defined order.
Define discrete process
Consist of a series of distinct operations with a definite condition for initiating each operation.
Define time-driven sequential process
Time-driven sequential processes move from one operation to the next due to a time interval expiring or an absolute time value being reached.
Define event driven sequential process.
Event driven sequential processes move from one operation to the next due to an event.
What does PLC stands for?
Programmable logic controller
Name the five different types of PLC programming languages.
Ladder diagram, sequential function charts, functional block diagram, structured text, instruction list.
State the four different sections of the PLC.
Central processing unit, input/output, communication, power supply.
State the four functions of the input/output interface section.
Termination, signal conditioning, isolation, indication.
Explain the termination function of the input/output section.
The field wiring from devices located on the machine or process attaches at the input/output modules.
Explain the signal conditioning function of the input/output section.
Incoming or outgoing field values are:
1) Converted to the appropriate type;
2) Amplified to the appropriate levels;
3) Filtered;
4) Other signal conditioning depends on the device connected.
Explain the isolation function of the input/output section.
Signals are both electrically and physically isolated via photo-optical sensors.
Explain the indication section of the input/output section.
An indicator lamp or LED is driven by the inputn for diagnostics to indicate input or output bit status, or operational status of a device.
Name the four modes of operation pf the SLC-500.
Run mode, program mode, single scan test mode, continuous scan test mode.
Explain the run mode of operation.
The PLC executes the program in this mode.
Explain the program mode of operation.
In this mode, the PLC can upload or accept a download of a program.
Explain the single scan test mode of operation.
In this mode, the PLC executes the program once, but the output relays are not energized.
Explain the continuous scan mode of operation.
In this mode, the PLC executes the program continuously, but the output relays are not energized.
Currently, the PLC is operating in run mode and the laptop is offline. You have just finished writing a new program. Explain the steps you would take to have the PLC run your new program.
You need to connect the laptop to the PLC and then go online. Once online, you need to put the PLC into program mode and then download the program.
Describe the XIC and XIO instructions and the result of each instruction when logic 0 then logic 1 is present at the indicated bit.
XIC is false when logic 0 is present and true when logic 1 is present.
XIO is true when logic 0 is present and false when logic 0 is present.
What switches are XIC and XIO akin to?
XIC is akin to a NO switch, XIO is akin to a NC switch.
What is the main difference between a TON and RTO instruction in terms of their operation?
The TON instruction has its accumulator reset when the rung goes false. The accumulator of the RTO is not reset when the rung goes false.
What do the mnemonics EN, DN, and TT refer to with respect to a timer?
EN means enable.
DN means done.
TT means timer is timing.
Explain how you would force bit 5 of the input file high as part of a troubleshooting procedure.
I would select bit 5 of the input file and install a force ON. Then I would enable the forces.
You notice that the FORCED I/O LED is blinking. What should you do?
It indicates that forces are installed but not enabled. I would thus enable the forces.
