Spectrum Controls 1746sc-NI8u - Manual (Page 17)

Chapter 1: Module Overview 5
Module Operation
The module’s input circuitry consists of eight differential analog inputs,
multiplexed into an A/D converter. The A/D converter reads the analog
input signals and converts them to digital counts. The input circuitry also
continuously samples the CJC sensors and compensates for temperature
changes at the cold junction (terminal block). The module can be used
with remote CJC sensor inputs. The sensors must be Analog Devices
AD592CN temperature transducers. The module will not accept other
CJC sensor inputs, and thermocouple inputs will not function properly if
incorrect CJC sensors are used.
Module Addressing
The module requires eight words each in the SLC processor’s input and
output image tables. Addresses for the module in slot e are as follows:
I:e.0-7 thermocouple/mV/V/mA, RTD, resistance or status
data for channels 0-7, respectively
O:e.0-7 configuration data for channels 0-7, respectively.
Compatibility with Thermocouple, Current, and
Millivolt Devices & Cables
The module is compatible with the following standard types of
thermocouples: B, E, J, K, N, R, S, T and C and extension wire.
Refer to appendices B and C for details. The module is also
compatible with a variety of voltage and current devices with an
output of ±50, ±100 mV, +500mV, ±2V, 0-5V, 1-5V, 0-10V, ±10V,
0-20mA, and 4-20mA.
To minimize interference from radiated electrical noise, we
recommend twisted-pair and highly shielded cables such as the
following:
Table 1.7 Recommendations to minimize
interference from radiated electrical noise
For This Type of Device We Recommend This Cable (or equivalent)
Thermocouple Type J EIL Corp. J20-5-502
Thermocouple Type K EIL Corp. K20-5-510
Thermocouple Type T EIL Corp. T20-5-502
Other Thermocouple Types consult with EIL Corp or other manufacturers
mV, V, mA devices Belden 8761, shielded, twisted-pair