Measurement Computing USB-TEMP-AI - Manual (Page 20)

USB-TEMP-AI User's Guide Specifications
20
Parameter Conditions Specification
Maximum working
voltage (signal +
common mode) V0x to V3x ±10.25 V max
Common mode rejection
ratio T0x to T3x, f
IN
= 60 Hz 100 dB
V0x to V3x, f
IN
= 60 Hz, all input
ranges
83 dB
ADC resolution 24 bits
ADC No missing codes 24 bits
Input coupling DC
Warm-up time 30 minutes min
Open thermocouple
detect T0x to T3x Automatically enabled when the channel pair is
configured for thermocouple sensor.
The maximum open detection time is 3 seconds.
CJC sensor accuracy T0x to T3x, 15 °C to 35 °C ±0.25 °C typ, ±0.5 °C max
T0x to T3x, 0 °C to 70 °C –1.0 to +0.75 °C max
Channel configurations
Table 2. Channel configuration specifications
Channel Category Conditions Max number of
sensors (all channels
configured alike)
T0x-T3x Disabled All temperature input channels are disconnected from screw
terminals and internally connected to GND. See Note 4
T0x-T3x Thermocouple
(Note 1) 4 differential channels
T0x-T3x Semiconductor
sensor (Note 1) 4 differential channels
T0x-T3x RTD and
Thermistor
(Note 1) 2-wire input configuration with a single sensor per channel
pair 2 differential channels
2-wire input configuration with two sensors per channel pair 4 differential channels
3-wire configuration with a single sensor per channel pair 2 differential channels
4-wire input configuration with a single sensor per channel
pair 2 differential channels
4-wire input configuration with two sensors per channel pair 4 differential channels
V0x-V3x Disabled All voltage input channels are disconnected from screw
terminals and internally connected to GND. See Note 4
V0x-V3x Differential
(Note 2) 4 differential channels
V0x-V3x Single-ended 4 single-ended channels
Note 1: Internally, the device has four, dual-channel, fully differential A/Ds providing a total of eight input
channels. The temperature input channels are configured as two channel pairs with T0x/T1x and
T2x/T3x accepting temperature sensor type inputs. This "channel-pairing" requires T0x/T1x, and
T2x/T3x to be configured to monitor the same category of temperature sensor. Mixing different sensor
types of the same category (such as a type J thermocouple on temperature channel 0 and a type T
thermocouple on temperature channel 1) is valid.
Note 2: The voltage input channels V0x, V1x, V2x, and V3x are not configured as channel pairs. Therefore
each channel can be configured independently. When connecting differential inputs to floating input
sources, you must provide a DC return path from each differential input to ground. To do this, simply
connect a resistor from each of the differential inputs to GND. A value of approximately 1 MΩ can be
used for most applications.