examine if closed |
A basic PLC input instruction that updates the output if the contact switches from open to closed. |
examine if open |
A basic PLC input instruction that updates the output if the contact switches from closed to open. |
handheld programmer |
A PLC programming device that combines a display screen and keypad all in one unit. Specially assigned keys allow you to enter program instructions, changes, and navigate and troubleshoot the PLC system. |
ladder logic |
The most common programming language for PLCs. Ladder logic is based on line diagrams. |
line diagram |
A diagram that shows the logic of an electrical circuit using standard symbols. Also known as a ladder diagram because the diagram appears as individual lines or "rungs" connected between two vertical lines, line diagrams can be converted into PLC ladder logic. |
logic |
The sequence of operations performed by a circuit or the sequence of instructions performed by a PLC. |
memory circuit |
A type of circuit that stores a charge and keeps the load energized even after the signal is removed. |
PLC wiring diagram |
A diagram that shows the locations that inputs and outputs are physically connected to PLC terminals. The physical locations do not directly affect the circuit logic. |
processor |
The main device that processes information and carries out instructions in a PLC. Also known as the CPU or controller. |
programmable logic controller |
A processor driven device that uses logic-based software to provide electrical control to machines. |
programming diagram |
A type of line diagram that uses the input and output symbols used by PLC ladder logic. Line diagrams are converted to programming diagrams before being entered into a PLC. |
rung |
One of multiple horizontal programming lines in a ladder logic diagram. Each rung controls one output. |
terminal |
A connecting point on PLC input and output modules to which a wire can be attached to connect a component. |
troubleshooting |
A method by which a problem is solved. Troubleshooting a PLC often involves using the prints as a guide to find the problem area. |
wiring diagram |
The most detailed of electrical prints. A wiring diagram shows the physical relationship of all the components, as well as the information needed to hardwire the circuit. |