The logic for the detection of a large box should be very much the same as the logic for the detection of the small box. We assume this is the case, and we create a new rung and edit the new rung to reflect the addresses that are unique to the large box detection.
When a large box passes through the sizing station, the small box sensors will also be energized. We will assume that one or both detectors for sensing a small box will be activated if a large box passes through the sizing station.
We delete the two XIO instructions that appeared in the small box detection logic, and we add two XIC instructions in parallel to Rung 2 to include the small box sensors.
Adding the confirmation of a small box sensor ensures that the counter is not incremented should something “wave” through the field of detection of the upper detectors.