A method and system for preventing the transmission of stale communications packets by a network multiplexer. The machines include a detection system adapted to detect one or more dangerous conditions between a person and the cutting tools, and a reaction system associated with the detection system. The switching device includes an analog switching circuit that selects one of a first pair of differential outputs of the first device having a first common mode voltage and a second pair of differential outputs of the replacement device having a second common mode voltage. The preferred merge symbol is added to the multilevel data sequence so that the RDS of the read signal is controlled. due to obstructions andor electromagnetic shields that may block portions of a wireless network access point signal at subsequent locations along the mapped path.