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.

Analog inputs use %AI references in the program

mable controller.  A maximum of 8K words of %AI

memory is currently available in the programmable

controller.  Each input channel uses one word (16 bits)

of %AI memory.

Field wiring is made to a removable terminal board

and the module is mechanically keyed to ensure cor

rect replacement with a similar module type in the

field.  I/O references are user configurable without the

use of jumpers or DIP switches on the module.

Configuration is done using the configuration func

tion of the MS-DOS or Windows programming soft

ware running on Windows 95 or Windows NT over

Ethernet TCP/IP or through the SNP port. The Pro

gramming Software configuration function is installed

on the programming device.  The programming de

vice can be an IBM  XT, AT, PS/2  or compatible Per

sonal Computer.