USB-TEMP User's Guide
Specifications
5-2
Channel configurations
Table 5-2. Channel configuration specifications
Sensor Category
Conditions
Specification
Disabled
Thermocouple
8 differential channels
Semiconductor sensor
8 differential channels
2-wire input configuration with a single sensor
4 differential channels
2-wire input configuration with two sensors
8 differential channels
3-wire configuration with a single sensor per channel pair
4 differential channels
RTD and thermistor
4-wire input configuration
8 differential channels
Note 1:
Internally, the USB-TEMP has four, dual-channel, fully differential A/Ds providing a
total of eight differential channels. The analog input channels are therefore configured in
four channel pairs with CH0/CH1 sensor inputs, CH2/CH3 sensor inputs, CH4/CH5
sensor inputs, and CH6/CH7 sensor inputs paired together. This "channel-pairing"
requires the analog input channel pairs 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 channel 0 and a type T thermocouple on channel 1) is valid.
Note 2:
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 3:
The factory default configuration is
Disabled
. The Disabled mode will disconnect the
analog inputs from the terminal blocks and internally ground all of the A/D inputs. This
mode also disables each of the current excitation sources.
Compatible sensors
Table 5-3. Compatible sensor type specifications
Parameter Conditions
J: -210 °C to 1200 °C
K: -270 °C to 1372 °C
R: -50 °C to 1768 °C
S: -50 °C to 1768 °C
T: -270 °C to 400 °C
N: -270 °C to 1300 °C
E: -270 °C to 1000 °C
Thermocouple
B: 0 °C to 1820 °C
100 ohm PT (DIN 43760: 0.00385 ohms/ohm/°C)
100 ohm PT (SAMA: 0.003911 ohms/ohm/°C)
RTD
100 ohm PT (ITS-90/IEC751:0.0038505 ohms/ohm/°C)
Thermistor
Standard 2,252 ohm through 30,000 ohm
Semiconductor / IC
TMP36 or equivalent
