eNotes: Mechatronics and Controls

6.2 IMPLEMENTATION FOR A PLC

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Consider the example of a parts buffer. Parts enter the buffer and are added to the top of the stack. The part at the bottom of the stack is checked and sorted (ejected differently) based on a quality check.

This can be implemented in ladder logic, but unlike the sequential techniques, there may be multiple tokens in the places, so counters are used to keep track of token counts.

For practice,