Configured for field termination and module interface execution in FLEX I/O network architectures, the Allen-Bradley 1794-TB3 (1794-TB3 Terminal Base Unit) provides direct physical/electrical execution.
Hardware Specifications
Parameter
Specification
Model
1794-TB3
Brand
Allen-Bradley
Origin
USA
Weight
0.63 lbs (0.28 kg)
Dimensions
Standard FLEX I/O base footprint
Operating Temp
-20 to 70 deg C
Power Consumption
Passive backplane load
Flexbus Voltage and Current
5 VDC, 640 mA
V/COM Supply Voltage
125 VAC/DC
V/COM Terminal Frequency
50/60 Hz
V/COM Terminal Current
10 A
Isolation Voltage
125 V continuous
Enclosure Rating
Open-Style
Clamp Type
Cage-Clamp
Terminal Screw Torque
0.56 to 0.79 Nm
Mounting Format
DIN-rail / Panel Mount
I/O Density Scaling and EtherNet/IP Deterministic Networks
The 1794-TB3 terminal base unit enables high I/O density scaling across FLEX I/O system layouts by providing 16 I/O connections alongside 18 power/common terminals. Internal routing pathways carry up to 640 mA of Flexbus current at 5 VDC to power attached operational hardware modules. Operating within EtherNet/IP deterministic networks, the base unit's internal backplane pass-through structure maintains signal integrity and continuous data bus speed while providing 125 V continuous channel-to-bus isolation.
Frequently Asked Questions
Q: Can an I/O module be attached or removed from the 1794-TB3 while power is applied to the backplane?
A: Yes. The 1794-TB3 houses the complete backplane interconnect circuitry, supporting Removal and Insertion Under Power (RIUP) of the installed module without disrupting backplane communications across neighboring node bases.
Q: What is the recommended tightening torque for the field terminal screws on the 1794-TB3?
A: The cage-clamp terminal screws must be torqued to a range between 0.56 and 0.79 Nm (5 to 7 lb-in) to ensure stable, low-resistance electrical contact without stripping the terminal assembly.
Field Installation Guidelines
Snap the terminal base onto a 35 mm steel DIN rail, ensuring the locking latch engages securely with the rail edge.
Push the base unit firmly against the adjacent adapter or terminal base to establish complete connection across the 5 VDC Flexbus interface.
Strip field conductors appropriately and insert them into the cage clamps, torquing screws precisely within the 0.56 to 0.79 Nm specification window.
Route power connections to the V/COM terminals using copper conductors rated for 125 VAC/DC up to 10 A continuous.
Verify that the DIN-rail grounding contact makes unpainted, low-impedance connection with earth ground to maintain proper isolation integrity.
