The National Instruments TB-2605 is a front-mounted screw terminal terminal block designed for enhanced multiplexing capabilities. This terminal block, identified by part number 777878-01, is compatible with the NI 2501 and NI 2503 switch cards and connects directly to the front panel I/O connectors of each PXI switch card. The TB-2605 features a printed circuit board construction with screw terminals, facilitating connections to thermocouples, voltage signals, thermistors, and resistance temperature detectors (RTDs). Its isothermal design minimizes temperature gradients across the terminals, while an integrated cold-junction temperature sensor boasts an accuracy of 0.5°C between 15 to 35°C, 0.9°C between 0° to 15°C, and 35° to 55°C, with a readability of 0.2°C and outputs ranging from 198.54 mV to 19.58 mV across specified temperature ranges.

The TB-2605 includes an analog bus plug for straightforward multiplexer expansion and provides two additional connectors on the front panel for convenient analog bus connections to neighboring switch cards. It measures 3.3 x 4.2 x 0.8 inches (8.4 x 10.7 x 2.0 cm) and is protected by an enclosure that maintains the isothermal environment required for optimal cold-junction sensor performance. Although National Instruments has announced the TB-2605 as obsolete, it remains available for purchase and service through Apex Waves. A comprehensive user manual and maintenance manual are available for download to assist in installation and operation.