What does the PLC Counter Instruction control?

What does the PLC Counter Instruction control?

• A. It provides control logic by setting and resetting its Done bit after it has been turned on and off a predetermined number of times instead of after a time delay
• B. It measures elapsed time
• C. It delays outputs by a fixed amount of time
• D. It duplicates the input on the output

Answer: (A)

The Counter Instruction is used to trigger actions after a specific number of signal activations rather than after a time delay. It watches an input, and each time that input goes on, it increments its accumulated count. When the count reaches the preset value, the Done bit is set, signaling that the target has been reached and allowing the rest of the logic to proceed. The counter can then be reset to start a new cycle as needed. This is distinct from measuring elapsed time, which is what a timer does, and from delaying outputs or copying the input to the output, which are not the functions of a counter.

The Counter Instruction is used to trigger actions after a specific number of signal activations rather than after a time delay. It watches an input, and each time that input goes on, it increments its accumulated count. When the count reaches the preset value, the Done bit is set, signaling that the target has been reached and allowing the rest of the logic to proceed. The counter can then be reset to start a new cycle as needed.

This is distinct from measuring elapsed time, which is what a timer does, and from delaying outputs or copying the input to the output, which are not the functions of a counter.