Multi-point analog to single-line input for a PLC system

摘要

A hardware/PLC logic combination which enables measurement of a plurality of analog voltage points (e.g., multiples of 8 points) on a single high speed PLC input without separate synchronization inputs or outputs. This is accomplished through the use of a multiplexer circuit [clock, binary counter, analog multiplexer, voltage to frequency converter], and a high speed counter function at the PLC. Synchronization between the PLC and circuit is through the detection of a fixed voltage on channel “one” of the circuit, which is set well above the typical range (e.g., 0-10V) of the remaining analog inputs.

主权项

1. A multiple channel system for a single input of a controller comprising:
a first multiplexer having a plurality of inputs and an output; a binary counter circuit coupled to the first multiplexer; and, a controller having a first input coupled to the output of the first multiplexer, the first input selectively receiving data from the plurality of inputs to the first multiplexer, wherein each input of the first plurality of inputs of the first multiplexer is coupled to a device providing an analog voltage signal.