Rockwell / Allen-Bradley 1794-TB3 FLEX I/O Terminal Base Unit

The Rockwell/Allen-Bradley 1794-TB3 is a FLEX I/O Terminal Base Unit that is a wiring termination point for distributed I/O installations within Allen-Bradley FLEX I/O systems. The unit features 16 I/O terminals with 3-wire cage clamp connections and accommodates a total of 52 terminals - 18 common terminals and 18 supply terminals (+V). Operating at 24V DC/AC or 120V DC/AC with maximum supply voltage of 125V AC/DC, the TB3 supports current capacity up to 10 A per terminal.

DIN rail mounted in a compact 94 mm × 94 mm × 69 mm form factor, it accepts solid or stranded copper wire from 0.34 mm² to 4 mm² (22 AWG to 12 AWG) with terminal screw torque of 0.56–0.79 Nm.

Technical Specifications

• Model: 1794-TB3


• Termination Type: 3-wire cage clamp


• I/O Terminals: 16


• Total Terminals: 52 (18 common, 18 supply)


• Maximum Current: 10 A per terminal


• Supply Voltage: 125V AC/DC, 50/60 Hz maximum; 24V DC/AC or 120V DC/AC operational


• Isolation Voltage: 125V continuous; module-dependent ratings up to 60V AC or 75V DC


• Backplane & FlexBus Current: 640 mA @ 5V DC each


• Wire Size: 0.34–4 mm² (22–12 AWG); solid or stranded copper, 75°C rated


• Terminal Torque: 0.56–0.79 Nm (5–7 lb-in)


• Dimensions: 94 × 94 × 69 mm (3.7 × 3.7 × 2.7 in)


• Weight: ~0.249 kg (0.5 lbs)


• Mount: DIN rail


• Enclosure: IP20 open-style

Key Features

• Cage clamp termination simplifies wiring and maintenance


• Supports multiple FLEX I/O module types: digital, analog, temperature, and specialty I/O


• Operating temperature range: −20°C to 70°C (−4°F to 158°F)


• Storage temperature: −40°C to 85°C


• Rated for 30G shock and 5G vibration (10–500 Hz)


• UL, cULus, CE, and RoHS certified

Compatibility & Integration The TB3 integrates with FLEX I/O modules including 1794-IA8, 1794-OA8, 1794-IB8, 1794-OB8, 1794-IB16D, 1794-IT8, 1794-IRT8, 1794-IR8, 1794-IF4I, and 1794-OF4I. Network communication supported through Remote I/O, DeviceNet, ControlNet, and EtherNet/IP via appropriate adapter modules.