Measurement Computing USB-TC-AI - Manual (Page 16)

USB-TC-AI User's Guide Specifications
16
Parameter Conditions Specification
Common mode rejection ratio T0x to T3x, fIN = 60 Hz 100 dB
V0x to V3x, fIN = 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 max 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 Specification
T0x to T3x Disabled All temperature input channels are disconnected from screw
terminals and internally connected to GND. See Note 4
T0x to T3x Thermocouple
Note 1 4 differential channels
V0x to V3x Disabled All voltage input channels are disconnected from screw
terminals and internally connected to GND. See Note 4
V0x to V3x Differential
Note 2 4 differential channels
V0x to V3x Single-ended 4 single-ended
channels
Note 1: Internally, the USB-TC-AI has four, dual-channel, fully differential A/Ds providing a total of eight
input channels.
Note 2: When connecting differential inputs to floating input sources, you must provide a DC return path from
each differential input to ground. To do this, connect a resistor from each of the differential inputs to
GND. A value of approximately 1Meg ohm can be used for most applications.
Note 3: Channel configuration information is stored in the EEPROM of the isolated microcontroller by the
firmware whenever any item is modified. Modification is performed by commands issued over USB
from an external application, and the configuration is made non-volatile through the use of the
EEPROM.
Note 4: The factory default configuration is Disabled. The Disabled mode will disconnect the temperature and
voltage inputs from the terminal blocks and internally connect ground (GND) to all of the A/D inputs.
Compatible sensors: T0x toT3x
Table 3. Compatible sensor type specifications
Parameter Conditions (°C)
Thermocouple J: –210 to 1200
K: –270 to 1372
R: –50 to 1768
S: –50 to 1768
T: –270 to 400
N: –270 to 1300
E: –270 to 1000
B: 0 to 1820