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July 2025
777878-01
777878-01, Front Mounting, Screw Terminal, TB-2605 Multiplexing Terminal Block
Actual item may vary if no part number is provided on quote request.
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Andrew Gar**** Verified Buyer
" Amazing to work with and had my order within 1 week after purchasing with all NI certs and data that were needed. "
March 2025
Said Sai**** Verified Buyer
" Competent contact for highly specialized components. The support team is very knowledgeable. Many thanks for the help and the fast shipping! "
January 2025
Bob C**** Verified Buyer
" Jason was able to get our emergency situation taken care of quickly and professionally. "
May 2025
Gregg Flecki**** Verified Buyer
" Great service and great products. This is my 2nd time using Apex Waves, truly impressed. "
January 2025
Carol Zimme**** Verified Buyer
" Very responsive and helpful, competitive pricing. Good source! "
July 2025
Andrew Gar**** Verified Buyer
" Amazing to work with and had my order within 1 week after purchasing with all NI certs and data that were needed. "
March 2025
Said Sai**** Verified Buyer
" Competent contact for highly specialized components. The support team is very knowledgeable. Many thanks for the help and the fast shipping! "
January 2025
Bob C**** Verified Buyer
" Jason was able to get our emergency situation taken care of quickly and professionally. "
May 2025
Gregg Flecki**** Verified Buyer
" Great service and great products. This is my 2nd time using Apex Waves, truly impressed. "
January 2025
National Instruments 777878-01 Terminal Block
National Instruments part number 777878-01 is an identifying part number for the TB-2605 Terminal Block. This is a front-mounting terminal block designed with screw terminals and multiplexing capabilities. It is compatible with NI 2501 and NI 2503 switch cards, connecting directly to their front panel I/O connectors. This terminal block features an analog bus plug for easy expansion of multiplexers. Enclosed to maintain an isothermal environment for the cold-junction sensor and screw terminals, the NI 777878-01 allows connections to each channel except the cold-junction sensor itself. It includes additional connectors on the front panel for linking to the analog bus of adjacent switch cards using a low-voltage AB plug.
Built with a printed circuit board and screw terminals, the TB-2605 supports thermocouples, voltage signals, thermistors, and RTDs. The isothermal design minimizes temperature gradients across terminals, while an accurate cold-junction temperature sensor ensures precise measurements with thermocouples. The cold-junction sensor offers an accuracy of 0.5°C from 15 to 35°C and 0.9°C from 0°C to 15°C, with readability and output of 0.2°C from 15 to 35°C and 198.54 mV to 19.58 mV from 0 to 55°C respectively.
To use the TB-2605 terminal block, you need an NI 2501 or 2503 switch card, the corresponding user manual, wire cutters, a 0.10 in. slotted screwdriver, wire insulation stripper, analog bus connectors, and a No. 1 Phillips screwdriver. To ensure accurate cold-junction compensation and maintain the terminal block's isothermal characteristics, position it and the chassis away from significant temperature variations. The connectors on both the switch card and terminal block are polarized, allowing for insertion in only one orientation. Users are advised to avoid forcing the terminal block when inserting or removing it from the NI 2501 or NI 2503 connector to prevent damage.
National Instruments has declared obsolete status for the NI 777878-01, however, it is still available for purchase and repairs at the Apex Waves website.
| Model | 777878-01 |
|---|---|
| Model Name | TB-2605 |
| Part Type | Terminal Block |
| Connectors | Screw Terminals |
| Compatible Switch Cards | NI 2501 and NI 2503 |
| Cold-junction Sensor Accuracy | 0.5° from 15 to 35 °C, 0.9° from 0° to 15° C,and 35 to 55 °C |
| Cold-junction Sensor Output | 198.54 mV to 19.58 mVfrom 0 to 55 °C |
| Maximum Voltage | Each input should remain within30 Vrms or 60 VDC of ground andall other channels to eliminate thepossibility of hazardous shock. |
| Cold-junction Sensor Repeatability | 0.2° from 15 to 35 °C |
| Dimensions | 3.3 by 4.2 by 0.80 in |
Associated part numbers for 777878-01:
National Instruments 777878-01 Frequently Asked Questions
Question: What is the purpose of part number 777878-01 (TB-2605)?
Answer: The terminal block accommodates thermocouples, resistance temperature detectors (RTDs), thermistors, and voltage signals.
Question: How do I know if I've installed the terminal block correctly?
Answer: The connectors on both the switch card and terminal block are polarized, allowing for insertion in only one direction.
Question: What is the maximum voltage this terminal block can accommodate?
Answer: Each input should remain within 30 Vrms or 60 VDC of ground and all other channels to eliminate the possibility of hazardous shock.
Question: How do you minimize the temperature gradient inside the 777878-01 (TB-2605) terminal block?
Answer: To minimize the temperature gradients, and maintain its isothermal nature for accurate cold-junction compensation, place the terminal block and chassis away from extreme temperature differentials.
777878-01 PDF Manuals
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