Spectrum Controls 1769sc-IF8u - Manual (Page 15)

Chapter 1: Module Overview 5
M o d u l e M o d u l e M o d u l e M o d u l e M o d u l e
O p e r a t i o n O p e r a t i o n O p e r a t i o n O p e r a t i o n O p e r a t i o n
When the module receives the input from an analog device, the module’s
circuitry multiplexes the input into an A/D converter. The converter reads
the signal and converts it as required for the type of input. If
thermocouples are being utilized, the module continuously samples the CJC
sensor and compensates for temperature changes at the terminal block
cold junction, between the thermocouple wire and the input channel. See
the block diagram below.
18-pin
Terminal
Block
CJC Input
RTD/Ohm/V/I/TC
Inputs
Input
Mux
2.5V Ref
Offset Calibration
Sigma Delta
ADC
2.5
MHz
O
p
tic
al
I
sol
at
io
n
Isolated
Power Supply
24V to +/-15V
5V Reg
+/-15V 5VI
80c51XA
processor w/
flash & SRAM
Mercury ASIC
24V
5V
5VD
LED
Isource
3.3V
Reg
3.3VD
500V DC Isolation
The module is designed to support up to 4 channels of RTD or resistance
and up to 8 channels of voltage, current, or thermocouple, but not
concurrently. For every channel of RTD or resistance the module
consumes 2 possible channels of voltage, current or thermocouple inputs.
This is due to terminal block limitations in a single board module. There
are five possible channel configuration combinations under this design
architecture. See table below.
Configuration Choices for the 1769sc-IF8u Configuration Choices for the 1769sc-IF8u Configuration Choices for the 1769sc-IF8u Configuration Choices for the 1769sc-IF8u Configuration Choices for the 1769sc-IF8u
8 channels Voltage/Current/Thermocouple + 0 channels RTD/Resistance
6 channels Voltage/Current/Thermocouple + 1 channels RTD/Resistance
4 channels Voltage/Current/Thermocouple + 2 channels RTD/Resistance
2 channels Voltage/Current/Thermocouple + 3 channels RTD/Resistance
0 channels Voltage/Current/Thermocouple + 4 channels RTD/Resistance