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Chapter 1
Introducing the OM-USB-TEMP-AI
Overview: OM-USB-TEMP-AI features
This user's guide contains all of the information you need to connect the OM-USB-TEMP-AI to your computer
and to the signals you want to measure.
The OM-USB-TEMP-AI is a USB 2.0 full-speed, temperature measurement module that is supported under
popular Microsoft
®
Windows
®
operating systems. The OM-USB-TEMP-AI is fully compatible with both USB
1.1 and USB 2.0 ports.
The OM-USB-TEMP-AI provides eight analog input channels that are configured as four differential
temperature inputs and four differential or single-ended voltage inputs. A 24-bit analog-to-digital (A/D)
converter is provided for each pair of analog inputs. Eight independent, TTL-compatible digital I/O channels
are provided to monitor TTL-level inputs, communicate with external devices, and to generate alarms. The
digital I/O channels are software programmable for input or output.
The temperature input channels are configured as two channel pairs that accept temperature sensor type inputs.
You can take measurements from four sensor categories. The sensor category is software programmable for
each channel pair:
Thermocouple – types J, K, R, S, T, N, E, and B
Resistance temperature detectors (RTDs) – 2, 3, or 4-wire measurements of 100 _ platinum RTDs
Thermistors – 2, 3, or 4-wire measurements
Semiconductor temperature sensors – LM36 or equivalent
You can connect a different category of sensor to each temperature channel pair, but you cannot mix sensor
categories between the channels that constitute a channel pair. You can, however, mix thermocouple types
within channel pairs.
Each voltage input channel is software configurable for differential or single-ended mode. The voltage input
range is software programmable for ±10 V, ±5 V, ±2.5 V, ±1.25 V.
The OM-USB-TEMP-AI provides a integrated cold junction compensation (CJC) sensor for thermocouple
measurements, and built-in current excitation sources for resistive sensor measurements.
An open thermocouple detection feature lets you detect a broken thermocouple. An on-board microprocessor
automatically linearizes the measurement data according to the sensor category.
The OM-USB-TEMP-AI is a standalone plug-and-play module which draws power from the USB cable. No
external power supply is required. All configurable options are software programmable.
The OM-USB-TEMP-AI is fully software calibrated.
