Functions

The High Level Analog Input subsystem for the  Pro

grammable Logic Controller (PLC) accepts analog in

puts of up to Ç10 volts full scale, or 4 to 20 milliamp

current loop signals.  These inputs are converted to

digital form for use by the CPU or other controllers

accessing analog inputs via the VME backplane.

Converted data is presented as 2’s complement (sign

+ 15 bits).  The basic converter is 14 bits resolution (1

part in 16384); an oversampling and averaging tech

nique further enhances this resolution.  Inputs are

protected against transient and steady-state overvol

tage conditions.