Watlow Electric Revision 5 - Manual (Page 28)

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5.5 ANALOG INPUT MODULES
Two types of analog input modules are available for the SYSTEM 32. The A32-
RRIAM -- REED RELAY ANALOG INPUT MODULE provides 16 analog
inputs with reed relay switching. The A32-SSAIM -- SOLID STATE ANALOG
INPUT MODULE provides 32 inputs with solid state switching. The A32-
SSAIM also provides 32 digital outputs for special systems. The primary
differences are:
The REED RELAY ANALOG INPUT MODULE provides 250Vdc
isolation between input channels and three wire switching: high, low, and
shield for each input. This module allows connection of three and four
wire RTD's and other special sensors. The REED RELAY ANALOG
INPUT MODULE is also recommended where high noise is present or
where grounded sensors are used and the ground potential difference will
exceed 10 Vdc.
The SOLID STATE ANALOG INPUT MODULE provides 32 inputs and
includes a high and low switch for each channel. The solid state switching
limits the channel to channel protection to 15Vdc. The SOLID STATE
ANALOG INPUT MODULE should be used with un-grounded sensors, or
sensors with the same ground potential [with-in 10Vdc].
5.6 A32-RRIAM -- REED RELAY ANALOG INPUT MODULE
The A32-RRAIM includes 16 analog inputs and a reference power supply. The
module can be plugged into any housing slot.
5.6.1 INPUT CIRCUITS
The ANAFAZE A32-RRAIM contains an isolated area that can be used to
install resistors to scale input voltages and connect inputs to match the -10
to 60mv (-16.7% to 100%) input range. The input circuit is designed to
enable connection of current inputs (such as 4 to 20ma), voltage inputs, and
for connection of transducers (RTD) in bridge configurations. ANAFAZE
will supply input scaling as needed -- order option A32-SI-XX. The input
circuit is shown below:
AUX O---------O---------O---------O
| | |RA
| | |
TERMINAL HI O-----------------------------O----HI
BLOCK |RE |RC |RB MEASUREMENT
| | | INPUT
LO O-------------------O---------O----LO
| |RD
| |
SHLD O---------O-------------------O----SH
RA, RB, RC, RD and RE are selected separately for each input and are
labeled on the PC board for each loop. CH 1 (channel 1) is loop 1 etc.
Resistors should be 0.1% metal film, 1/4 watt. Other components such as