Measurement Computing WLS-TEMP - Manual (Page 13)

WLS-TEMP Specifications
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Do not connect two different sensor categories to the same channel pair
The WLS-TEMP provides a 24-bit A/D converter for each channel pair. Each channel pair can monitor one
sensor category. To monitor a sensor from a different category, connect the sensor to a different channel pair
(input terminals).
Current excitation output
The WLS-TEMP has four dedicated pairs of current excitation output terminals (± I1 to ± I4 ). These terminals
have a built-in precision current source to provide excitation for the resistive sensors used for RTD and
thermistor measurements.
Each current excitation terminal is dedicated to one pair of sensor input channels:
 I1+ is the current excitation source for channel 0 and channel 1
 I2+ is the current excitation source for channel 2 and channel 3
 I3+ is the current excitation source for channel 4 and channel 5
 I4+ is the current excitation source for channel 6 and channel 7
Four-wire, two sensor common
Terminals 4W01 , 4W23 , 4W45 , and 4W67 are used as the common connection for four-wire configurations with
two RTD or thermistor sensors.
Two sensor common
Terminals IC01 , IC23 , IC45 , and IC67 are used as the common connection for two-wire configurations with two
RTD or thermistor sensors.
CJC sensors
The WLS-TEMP has two built-in high-resolution temperature sensors. One sensor is located on the right side,
and one sensor is located at the left side.
Digital I/O
You can connect up to eight digital I/O lines to the screw terminals labeled DIO0 to DIO7 . Each terminal is
software-configurable for input or output.
Power output
The two +5V output terminals are isolated (500 VDC) from the USB +5V.
Caution! The +5V terminal is an output. Do not connect an external power supply to this terminal or you
may damage the WLS-TEMP and possibly the computer.
Ground
The six ground terminals ( GND ) provide a common ground for the input channels and DIO bits, and are isolated
(500 VDC) from the USB GND.
Thermocouple connections
A thermocouple consists of two dissimilar metals that are joined together at one end. When the junction of the
metals is heated or cooled, a voltage is produced that correlates to temperature.
The WLS-TEMP makes fully-differential thermocouple measurements without the need of ground-referencing
resistors. A 32-bit floating point value in either a voltage or temperature format is returned by software. An
open thermocouple detection feature is available for each analog input which automatically detects an open or
broken thermocouple.
Use InstaCal to select the thermocouple type (J, K, R, S, T, N, E, and B) and one or more sensor input channels
to connect the thermocouple.