Programmable Logic Controller (PLC) Questions and Answers –
Suppose we have a Siemens S7-200 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 Siemens PLC, determining the statuses of the two lamps provided neither switch is pressed by a human operator:
Answer :
Output Q 0.1 will activate to energize lamp Y, but the other output (and lamp) will remain off.
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