Allen-Bradley 1794-TB3G Terminal Base Units
Configured for high-density wiring termination in Flex I/O backplane architectures, the Allen-Bradley 1794-TB3G (1794-TB3G Terminal Base Unit) provides direct physical/electrical execution. This 3-wire grounded screw-terminal base provides pass-through signal connection paths and power bus distribution for compatible 1794 Flex I/O functional modules without interrupting field wiring circuits during module swap operations.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | 1794-TB3G |
| Brand | Allen-Bradley |
| Origin | USA |
| Weight | 0.26 kg (0.56 lbs) |
| Dimensions | Standard 1794 Base Form Factor |
| Operating Temp | -20 to 70 deg C |
| Storage Temp | -40 to 85 deg C |
| Power Consumption | Passive Base Assembly |
| Supply Voltage Rating | 31.2 VAC/DC max |
| Line Frequency Range | 50 to 60 Hz |
| Maximum Current Rating | 10 A |
| Isolation Voltage | 2500 VDC |
| Wire Size | 24 to 16 AWG |
| Terminal Screw Torque | 0.56 to 0.79 Nm |
| Relative Humidity | 5 to 95% (non-condensing) |
| Vibration Resistance | 5 g @ 10 to 500 Hz |
Backplane Bus Communication and Signal Routing Integrity
The 1794-TB3G integrates an internal backplane bus interface designed to maintain backplane bus communication velocity and signal continuity across adjacent Flex I/O modules. The internal bus structure carries deterministic control signals and field power across the DIN-rail mounted cluster. Channel-to-channel and bus-to-field isolation limits are strictly enforced up to 2500 VDC to prevent common-mode noise propagation across backplane lines. The grounded terminal layout suppresses signal cross-talk and EMI interference, stabilizing analog and discrete I/O signal transmission paths across EtherNet/IP and ControlNet adapter nodes.
Frequently Asked Questions
Q: Can the 1794-TB3G terminal base remain fully wired while replacing an I/O module?
A: Yes. The base unit retains all physical field wiring connections, allowing the upper 1794 functional I/O module to be removed and installed under RIUP (Removal and Insertion Under Power) guidelines without disturbing field circuit terminations.
Q: What is the maximum allowable wire gauge and torque for terminal connection screws?
A: The terminal blocks accept solid or stranded conductors ranging from 24 to 16 AWG. Screw terminals must be tightened to a torque specification between 0.56 and 0.79 Nm to maintain electrical contact stability and prevent thread stripping.
Q: How does isolation voltage protection operate on this base unit?
A: The unit features a 2500 VDC galvanic isolation barrier engineered to separate field-side power and signal wiring from the low-voltage backplane logic bus, protecting backplane communication links from field surges.
Field Installation Guidelines
- DIN-Rail Mounting: Latch the 1794-TB3G securely onto a standard 35 mm DIN rail (EN 50022). Ensure the backplane connectors on adjacent bases interlock firmly to maintain backplane bus continuity.
- Field Wiring: Strip conductors back to manufacturer length specifications. Terminate signal wires into designated screw terminals using wire sizes from 24 to 16 AWG. Torque all terminal screws to 0.56–0.79 Nm.
- Shield Grounding: Connect cable shields to designated ground terminals on the base or to a central cabinet earth bus. Maintain low-impedance ground bonding to maximize noise immunity.
- Power Routing: Verify supply voltage levels do not exceed 31.2 VAC/DC and total bus current load does not exceed 10 A prior to applying line power.
Allen-Bradley 1794-TB3G Terminal Base Units
Allen-Bradley 1794-TB3G Terminal Base Units
Configured for high-density wiring termination in Flex I/O backplane architectures, the Allen-Bradley 1794-TB3G (1794-TB3G Terminal Base Unit) provides direct physical/electrical execution. This 3-wire grounded screw-terminal base provides pass-through signal connection paths and power bus distribution for compatible 1794 Flex I/O functional modules without interrupting field wiring circuits during module swap operations.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | 1794-TB3G |
| Brand | Allen-Bradley |
| Origin | USA |
| Weight | 0.26 kg (0.56 lbs) |
| Dimensions | Standard 1794 Base Form Factor |
| Operating Temp | -20 to 70 deg C |
| Storage Temp | -40 to 85 deg C |
| Power Consumption | Passive Base Assembly |
| Supply Voltage Rating | 31.2 VAC/DC max |
| Line Frequency Range | 50 to 60 Hz |
| Maximum Current Rating | 10 A |
| Isolation Voltage | 2500 VDC |
| Wire Size | 24 to 16 AWG |
| Terminal Screw Torque | 0.56 to 0.79 Nm |
| Relative Humidity | 5 to 95% (non-condensing) |
| Vibration Resistance | 5 g @ 10 to 500 Hz |
Backplane Bus Communication and Signal Routing Integrity
The 1794-TB3G integrates an internal backplane bus interface designed to maintain backplane bus communication velocity and signal continuity across adjacent Flex I/O modules. The internal bus structure carries deterministic control signals and field power across the DIN-rail mounted cluster. Channel-to-channel and bus-to-field isolation limits are strictly enforced up to 2500 VDC to prevent common-mode noise propagation across backplane lines. The grounded terminal layout suppresses signal cross-talk and EMI interference, stabilizing analog and discrete I/O signal transmission paths across EtherNet/IP and ControlNet adapter nodes.
Frequently Asked Questions
Q: Can the 1794-TB3G terminal base remain fully wired while replacing an I/O module?
A: Yes. The base unit retains all physical field wiring connections, allowing the upper 1794 functional I/O module to be removed and installed under RIUP (Removal and Insertion Under Power) guidelines without disturbing field circuit terminations.
Q: What is the maximum allowable wire gauge and torque for terminal connection screws?
A: The terminal blocks accept solid or stranded conductors ranging from 24 to 16 AWG. Screw terminals must be tightened to a torque specification between 0.56 and 0.79 Nm to maintain electrical contact stability and prevent thread stripping.
Q: How does isolation voltage protection operate on this base unit?
A: The unit features a 2500 VDC galvanic isolation barrier engineered to separate field-side power and signal wiring from the low-voltage backplane logic bus, protecting backplane communication links from field surges.
Field Installation Guidelines
- DIN-Rail Mounting: Latch the 1794-TB3G securely onto a standard 35 mm DIN rail (EN 50022). Ensure the backplane connectors on adjacent bases interlock firmly to maintain backplane bus continuity.
- Field Wiring: Strip conductors back to manufacturer length specifications. Terminate signal wires into designated screw terminals using wire sizes from 24 to 16 AWG. Torque all terminal screws to 0.56–0.79 Nm.
- Shield Grounding: Connect cable shields to designated ground terminals on the base or to a central cabinet earth bus. Maintain low-impedance ground bonding to maximize noise immunity.
- Power Routing: Verify supply voltage levels do not exceed 31.2 VAC/DC and total bus current load does not exceed 10 A prior to applying line power.
