OM-WEB Series User's Guide
Signal I/O Connections
22
Figure 7. Four-wire, single RTD or thermistor sensor measurement configuration
Four-wire, two-sensor
A four-wire, two-sensor measurement configuration is shown in Figure 8.
Note
: There are two high/low
channel pairs on each terminal. The # indicates the channel number. Do not make connections to the pin labeled
"NC".
Figure 8. Four-wire, two RTD or thermistor sensors measurement configuration
When configured for four-wire, two-sensor mode, both sensors must be connected to obtain proper
measurements.
Semiconductor sensor measurements (OM-WEB-TEMP only)
Semiconductor sensors are suitable over a range of approximately -40
C to 125
C, where an accuracy of
±2
C is adequate. The temperature measurement range of a semiconductor sensor is small when compared to
thermocouples and RTDs. However, semiconductor sensors can be accurate, inexpensive and easy to interface
with other electronics for display and control.
The OM-WEB-TEMP makes high-resolution measurements of semiconductor sensors and returns a 32-bit
floating point value in either a voltage or temperature format.
Use InstaCal or the web interface to select the sensor type (LM35, TMP35 or equivalent) and the sensor input
channel to connect the sensor.
Wiring configuration
Connect a semiconductor sensor using a single-ended configuration, as shown in Figure 9 on page 23. The #
indicates the channel number. Do not make connections to pins labeled "NC".
Note
: There are two high/low
channel pairs on each terminal. The # indicates the channel number. Do not make connections to the pin labeled
"NC". The OM-WEB-TEMP also provides
+5V
and
GND
pins for powering the sensor, but use of this power
source requires overriding the isolation between analog and power ground by connecting AGND to GND.
