National Instruments TBX-1303 Isothermal Terminal Block

The NI TBX-1303 (Part Number: 777207-03) is an isothermal, 32-channel Terminal Block designed for use with the SCXI-1100, SCXI-1181, SCXI-1102, and SCXI-1102B/C with thermocouples. However, this DIN rail-mountable Terminal Block is an effective solution for general-purpose applications as well. This model comes with various exclusive features for thermocouples, such as automatically ground-referencing, open-thermocouple loop detection capability, isothermal construction, and more.

To reduce thermal gradients, special plastic reinforced packing material is utilized in this Terminal Block. The NI TBX 1303 offers a high-impedance path to ground when used with the SCXI-1102 or SCXI-1102B/C signal conditioning units. Thus, the user’s system operates reliably with either ground-referenced or floating thermocouples. With the SCXI-1100, users can define the channels to be floating or ground referenced in segments of eight channels.

For general-purpose and routine applications, the TBX-1303 comes featured with 108 terminals, including: shield, CH+, and CH- for every input channel. For cold-junction compensation, this Terminal Block provides a thermistor temperature sensor, enabling the user to utilize thermocouples with SCXI modules. In its standard configuration, the TBX-1303 operates in multiplexed temperature sensor mode. However, the user can also set it to run in direct temperature sensor mode.

Over the temperature range of 0 to 55 °C, the temperature sensor voltage output of NI TBX-1303 varies from 1.91 to 0.58 V. A maximum voltage output accuracy of ±0.65 °C can be achieved within the 15 to 35 °C temperature range. For open thermocouple detection, a pull-up resistor is used between +5 V and CH+ and a bias resistor is used between chassis ground and CH–.

TBX-1303 Obsolete Status has been declared by National Instruments, but the Terminal Block will still be available for purchase and repairs by Apex Waves.