National Instruments SCXI-1303 Isothermal Terminal Block

The SCXI-1303 (Part Number: 777687-03) 32-Channel Terminal Block is recommended for use with the following SCXI modules: the SCXI- 1100/1102/1102B/1102C. This Terminal Block is suggested for high-precision thermocouple temperature measurement applications. The National Instruments NI SCXI-1303 has an extremely precise thermistor cold-junction temperature sensor, as well as an isothermal copper plane to reduce the temperature gradients across the screw terminals when the user completes measurements with thermocouples. The NI SCXI 1303 has special functions such as open thermocouple detection, signal ground referencing, and isothermal.

This Terminal Block has 78 screw terminals to ensure signal connection with ease. Thirty-two pairs of screw terminals join to the 32 differential inputs of the SCXI modules. A single pair of terminals attaches to the chassis ground pins on the module. In addition, three terminals link to the SCXI module OUTPUT and AOREF pins, along with to the SCXIbus GUARD. The remaining terminals are saved for the future.

The circuitry of the SCXI-1303 Terminal Block aids the user in perceiving an open thermocouple. To distinguish if any thermocouple is open, the user can determine if the matching SCXI module channel is saturated. The NI SCXI-1303 also has pullup and bias resistors that saturate the channel by applying +5 V at the open channel’s input. The outcome is saturation to the positive rail. The SCXI 1303 can be used with 10 Ω and 10 MΩ bias resistors. The 10 MΩ resistors are meant for use with the SCXI-1102/B/C modules, while the 10 Ω resistors are meant for use with the SCXI-1100 module. The bias resistors can be easily replaced by the user. The device is equipped with a thermistor cold-junction sensor which has an accuracy of 0.5 °C from 15 to 35 °C, 0.9 °C from 0 to 15 °C, and 35 to 55 °C. It has an output of 1.91 to 0.58 V from 0 to 55 °C. The NI device is run using the NI-DAQ driver software which is compatible with software packages such as LabVIEW and LabWindows/CVI.

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