Programmable Logic Controller (PLC) Questions and Answers
Suppose we have an Allen-Bradley model PLC connected to a pair of pushbutton switches and light bulbs as shown in this illustration:
Examine the following relay ladder logic (RLL) program for this Allen-Bradley PLC, determining the necessary switch statuses to energize lamp Y, and the necessary switch statuses to energize switch Z:
Answer :
- To energize lamp Z: press switch B, release switch A.
- To energize lamp Y: press switch A, release switch B.
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