Owner's manual

OM-USB-TEMP User's Guide Specifications

Channel configurations

Table 2. Channel configuration specifications

Sensor Category Conditions Max number of

sensors (all channels

configured alike)

Disabled

Thermocouple 8 differential channels

Semiconductor sensor 8 differential channels

2-wire input configuration with a single sensor per channel pair 4 differential channels

2-wire input configuration with two sensors per channel pair 8 differential channels

3-wire configuration with a single sensor per channel pair 4 differential channels

4-wire input configuration with a single sensor per channel pair 4 differential channels

RTD and thermistor

4-wire input configuration with two sensors per channel pair 8 differential channels

Note 1: Internally, the OM-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 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