Expansion Bus

The bottom six terminals (35 through 40) on the ter

minal board on the Base Converter and Expander

modules make up an expansion bus for connecting

input Expander modules to the Base Converter mod

ule.  An analog multiplexer on the Expander module

acts as a switching circuit to connect analog inputs,

one at a time, to the A/D (Analog to Digital) converter

on the Base Converter module.

Each expander channel is updated every 2.8 x N ms

(where N = total number of Expander channels pres

ent).  Note that the scan sequence is free running and

it cannot be synchronized with any external event.

Also note that all inputs of an Expander module will be

scanned even if they are not being used.