Abstract: A method of transmitting a signal to at least one of a plurality of serially-connected devices. The method includes the step of receiving the signal at a first one of the plurality of serially-connected devices, where the signal includes a first address. Then, the signal is sent to each successive device of the plurality of serially-connected devices. Prior to the step of sending the signal to the each successive device, the first address of the signal is modified by a predetermined value at each of the plurality of serially-connected devices. Data associated with the signal can be transmitted to or received from at least one of the plurality of serially-connected devices if the first address received by the one of the plurality of serially-connected devices matches a predetermined address. The method is useful in the operation of programmable limit switches (PLS), especially in a PLS where each output circuit has an addressable controller.

Abstract: A programmable limit switch includes output channels for receiving position data, each position value of the position data representing an incremental advance of a workpiece through a production field, and for producing actuation signals. The channels are connectable to respective output devices responsive to the respective actuation signals and located in the field. Each output channel has an output controller, which is individually programmable to change the state of respective actuation signals in response to reaching selected position values. Preferably, the PLS includes input connectors coupled to a respective channel and connectable to respective input devices located within the production field. Each channel operates its own inputs and outputs according to a variety of programmed functions depending upon system conditions seen by the output controller.