Allen-Bradley 1794-TB3T Flex I/O Terminal Base Unit

Configured for high-density signal distribution in Flex I/O platforms, the Allen-Bradley 1794-TB3T (1794-TB3T Terminal Base Unit) provides direct physical mounting and electrical termination for up to 16 I/O points within the Flex I/O architecture.

Hardware Specifications

I/O Density Scaling and Backplane Connectivity

The 1794-TB3T facilitates I/O density scaling by providing a modular foundation for 1794 series modules. The base unit serves as a passive pass-through interface, connecting field-side wiring directly to the mounted I/O module and the internal Flex I/O backplane bus. Its physical construction supports consistent communication velocity across the I/O rack, provided that all modules are seated with the locking mechanism fully engaged to maintain signal integrity across the bus interface.

Frequently Asked Questions

Q: Does the 1794-TB3T provide electrical isolation for the I/O signals?

A: No. The 1794-TB3T is a passive terminal base. Electrical isolation characteristics are determined solely by the specific 1794 I/O module installed on the base, not by the base unit itself.

Q: Is this terminal base compatible with all 1794 series modules?

A: The 1794-TB3T is compatible with most 1794 Flex I/O modules; however, users must verify the specific pin-out and wiring requirements of the I/O module to ensure compatibility with the terminal base’s wiring configuration.

Field Installation Guidelines

• DIN-Rail Mounting: Ensure the unit is installed on a 35 mm DIN rail. Secure the base to the rail using the integrated locking tab to maintain stability in environments subjected to the specified 5 g vibration resistance limit.
• Grounding: Utilize the 8 chassis ground terminals to terminate cable shields. A solid, low-impedance connection to the cabinet's main ground bus is required to mitigate electromagnetic interference in signal lines.
• Wiring Limitations: The terminal base supports up to 125 VAC/DC. Ensure that wire gauges used for field termination comply with local electrical codes and the 10 A current rating limit of the terminal base unit.
• Environmental Sealing: While the unit operates between 5% and 95% relative humidity (non-condensing), ensure the control cabinet is rated appropriately for the operating environment to prevent moisture accumulation on the exposed terminal screws.