RSLogix PLC Programming Latches instruction


• Goal: To learn how latches work

• Instructions:

  1. Go offline and enter the following ladder logic.

  1. Download the ladder logic and observe how the switches change the operation of the latches. Notice that the second last line of ladder logic has no effect: this is because the output ‘O:0/2’ was used twice, and only the last use counts.

  2. After a latch is set (O:0/1) turn off the PLC, and turn it back on. Do the latched outputs stay latched? The programming software will give an error message “Communications loss to processor“, just click “retry” to reconnect to the PLC.

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