The Allen-Bradley 1794-TBN, also cataloged as the 1794-TBN FLEX I/O Terminal Base Unit, operates as a dedicated hardware component for field signal termination and backplane bus routing within FLEX I/O control systems.
Hardware Specifications
Parameter
Specification
Model
1794-TBN
Brand
Allen-Bradley
Origin
USA
Weight
0.56 lbs (0.26 kg)
Dimensions
Standard FLEX I/O base footprint
Operating Temp
-20 to 70 deg C
Power Consumption
Passive backplane load
Voltage Rating
250 VAC/DC
Current Rating
10 A max
Wire Size
22 to 12 AWG (0.35 to 2.5 mm sq)
Frequency Rating
50 to 60 Hz
Isolation Voltage
250 V continuous
I/O Capacity
16 I/O Terminals
Power Terminals
2 Common Terminals
Terminal Screw Torque
1.4 Nm (12 lb-in)
Operating Humidity
5 to 95% non-condensing
Mounting Format
DIN-rail / Panel Mount
Firmware Flash Compatibility and I/O Density Scaling
The 1794-TBN terminal base provides physical interconnectivity and signal scaling for high-density 16-point FLEX I/O modules without requiring hardware firmware flashing. It establishes high-bandwidth signal paths between field sensors and the backplane adapter while maintaining strict channel isolation up to 250 V. Designed for high I/O density scaling across backplane networks, the passive terminal routing maintains deterministic communication velocity and eliminates data packet distortion during parallel field signal updates to host controller nodes.
Frequently Asked Questions
Q: Does removing the active I/O module attached to the 1794-TBN interrupt backplane communications to downstream modules?
A: No. The internal backplane bus pass-through circuit is contained entirely within the 1794-TBN base structure, enabling Removal and Insertion Under Power (RIUP) of the active module without disrupting adjacent network nodes.
Q: What is the primary difference between the 1794-TBN and standard FLEX I/O terminal bases?
A: The 1794-TBN utilizes NEMA-style screw-clamp terminations rated for higher terminal tightening torque (1.4 Nm) and operating temperatures up to 70 deg C, providing enhanced mechanical retention in severe vibration environments.
Field Installation Guidelines
Mount the terminal base onto an earth-grounded 35 mm DIN rail, verifying that the rear rail locking latch engages completely.
Slide the unit laterally against the adjacent base or adapter module until the backplane expansion connectors seat fully.
Wire field conductors to the 16 I/O terminals using 22 to 12 AWG wire, torquing screw terminals precisely to 1.4 Nm (12 lb-in).
Terminate common supply lines to the 2 dedicated common terminals to form a continuous return pathway.
Ensure the base grounding plate makes clean, paint-free metallic contact with the DIN rail to preserve EMC isolation performance.
