Measurement Computing USB-TEMP-AI - Manual (Page 6)

6
Chapter 1
Introducing the USB-TEMP-AI
The USB-TEMP-AI is a USB 2.0 full-speed, temperature measurement module that is supported under popular
Microsoft
® Windows ® operating systems. The USB-TEMP-AI is fully compatible with both USB 1.1 and USB
2.0 ports.
The 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 Ω platinum RTDs
 Thermistors – 2, 3, or 4-wire measurements
 Semiconductor temperature sensors – LM35, TMP35 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 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 USB-TEMP-AI features eight independent temperature alarms. Each alarm controls an associated digital
I/O channel as an alarm output. The input to each alarm is one of the temperature input channels. The output of
each alarm is software configurable as active high or low. You set up the temperature threshold conditions to
activate each alarm. When an alarm is activated, the associated DIO channel is driven to the output state.
The 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 USB-TEMP-AI is fully software calibrated.