Programmable Logic Controllers

Hardware

100

This is the "brain" of the PLC where logic is processed.

The processor.

200

The part of the PLC connects it to real-world devices.

I/O Modules.

300

This component converts standard high-voltage power into the low DC voltage the PLC needs.

Power Supply

400

This is the laptop or PC used to write the program and download it.

Programming Device.

500

This is the physical rack or rail that allows all the modules to talk to the CPU.

Backplane

Processor Scan

100

In this step, the PLC checks which buttons or sensors are pressed.

Input Scan

200

In this step, the PLC reads the ladder program from left to right, top to bottom.

Program Scan

300

During this step of the scan, the processer performs diagnostic checks.

Housekeeping

400

This step is when the PLC finally sends power to the motors or lights.

Output scan

500

During operation, a PLC performs a series of steps continuously. This is called the _______.  

The scan cycle

Ladder Logic

100

These are the horizontal lines that hold code instructions.

Rungs

200

A contact that only lets "power" through when it is activated (pushed).

N/O, XIC

300

A contact that stays "closed" (on) until it is activated.

N/C, XIO

400

The symbol at the far right of a rung that represents the device you are controlling.

Output(OTE)

500

Placing two contacts in parallel creates what type of logic gate?

OR gate

Analog and Discrete

100

A simple ON or OFF signal, like a standard light switch.

Discrete

200

A variable signal that can represent a range, like 0 to 100 degrees.

Analog

300

A sensor that detects if a box is present or not is this type of input.

Discrete

400

A sensor that tells you exactly how much liquid is in a tank is this type of signal.

Analog

500

This type of signal is usually measured in voltage (0-10V) or current (4-20mA).

Analog signal

Timers and Counters

100

This instruction is used to delay an action, like waiting 5 seconds before a belt starts.

TON, on delay

200

This instruction tracks how many items have passed a sensor.

Counter(CTU, CTD)

300

This is the "goal" number you type into a timer or counter.

Preset

400

This is the "live" number showing the current time or count as it happens.

ACC

500

You must use this instruction to move a counter or timer back to zero.

reset instruction(RES)