Spectrum Controls 1771sc-IFE32 - Manual (Page 11)

Chapter 1: Overview of the Analog Input Module 1
Chapter 1
Overview of the Analog Input Module
Chapter Objectives
This chapter, we describe:
· features of the module
· how the module communicates with programmable controllers
Module Description
The analog input module is an intelligent block transfer module that interfaces analog
input signals with any Allen-Bradley programmable controllers that have block
transfer capability. Block transfer programming moves input data words from the
module’s memory to a designated area in the processor data table in a single scan. It
also moves configuration words from the processor data table to module memory.
The input module is a single-slot module and requires no external power supply. (If
using passive transducers for input, the user must supply loop power.) After scan-
ning the analog inputs, the input data is converted to a specified data type in a digital
format to be transferred to the processor’s data table on request. The block transfer
mode is disabled until this input scan is complete. Consequently, the minimum
interval between block transfer reads is the same as the total input update time for
each analog input module.
Features
The Analog input module senses up to 32 single-ended or 16 differential analog
inputs and converts them to a proportional four-digit BCD, 16 bit binary and 12 bit
binary formats. You can select from five voltage or three current input ranges.
Channels may be configured to acquire data as singled-ended inputs or as differential
pairs. During differential acquisition, odd channels (1, 3, 5, etc.) are the positive input
and the even channels (2, 4, 6, etc.) the negative inputs. A channel pair consists of
two consecutive channels (1&2, 3&4, 5&6, etc.). Within a channel pair both channels
must be specified as single acquisition or both as differential acquisition. Within a
group of 8 consecutive channels, all 8 channels must be from either 8 voltage or 8
current sources. If part of a voltage group, a channel may be any of the allowed
voltage ranges and if in a current group a channel may be any of the allowed current
ranges as long as all 8 are either voltage ranges or all 8 are current ranges.
This module’s program selectable features include:
· 32 single-ended or 16 differential inputs
· User program selectable input ranges on a per channel basis (see table)
· Selectable real-time sampling
· Selectable scaling to engineering units
· Selectable digital filtering
· Selectable data format