This uses a ring bus system ( Figure 13.38) with all devices actively connected to a closed-loop signal transmission path.
One network that is used for such simple discrete on/off signals is InterBus-S. Thus a sensor may be used to detect whether there is a bottle in front of it and whether it is full of liquid, the sensor then giving the appropriate signal for the bottle to be diverted from the line into a box.
Automated assembly lines basically tend to involve sensors placed along the line to detect whether items are present or not.
