Allen-Bradley 1794-TB3 – Master Relay Module | FLEX I/O Platform
Engineering Background
The Allen-Bradley 1794-TB3 is a terminal base unit within Rockwell Automation’s FLEX I/O system — a modular, distributed I/O platform engineered for high-density signal termination in demanding industrial environments. The TB3 variant provides a master relay output interface, enabling direct relay-driven load control without external relay panels, reducing panel footprint and wiring complexity.
Product Positioning
Designed for procurement engineers and system integrators who require a verified, drop-in replacement or expansion component for existing FLEX I/O architectures. The 1794-TB3 is the preferred termination base when relay-isolated outputs are mandated by safety or load specifications. It is fully compatible with the 1794 adapter and I/O module ecosystem, making it a zero-risk addition to any ControlLogix, CompactLogix, or SLC-based distributed I/O network.
Complete Technical Specifications
- Catalog Number: 1794-TB3
- Manufacturer: Allen-Bradley / Rockwell Automation
- Series: FLEX I/O
- Module Type: Master Relay Terminal Base
- Relay Output Type: Electromechanical relay, Form C (SPDT)
- Number of Relay Outputs: 8 (per module configuration)
- Output Voltage Range: 24V DC / 120–240V AC
- Maximum Output Current: 2A per output (resistive load)
- Isolation: Optically isolated between field side and backplane
- Backplane Communication: FLEX I/O backplane bus
- Power Consumption: Supplied via FLEX I/O power supply module
- Operating Temperature: 0°C to +60°C (32°F to 140°F)
- Storage Temperature: -40°C to +85°C
- Relative Humidity: 5% to 95% non-condensing
- Enclosure Rating: Open type — requires installation in rated enclosure
- Mounting: DIN rail (35mm) via FLEX I/O adapter
- Weight: Approx. 200 g
- Certifications: UL Listed, CE Marked, cUL
- Country of Origin: USA
Proven Application Environments
- Discrete Manufacturing: Conveyor control, motor starter interlocking, and machine safety relay circuits
- Process Industries: Valve actuation, pump control, and alarm annunciator outputs in oil & gas and chemical plants
- Building Automation: HVAC relay switching, lighting control panels, and BMS integration
- Automotive Assembly: Weld controller interfaces and fixture clamping relay outputs
- Water & Wastewater: Pump station control and remote telemetry relay outputs
- Food & Beverage: Hygienic machine control with relay-isolated actuator outputs
Engineering Advantages
- Relay Isolation: Galvanic isolation between control logic and field loads eliminates ground loop interference and protects PLC backplane from inductive transients
- Universal Load Compatibility: Handles both AC and DC loads on the same module — reduces BOM complexity in mixed-voltage panels
- Hot-Swap Capable: FLEX I/O architecture supports module removal and insertion under power (with appropriate adapter configuration), minimizing unplanned downtime
- Compact Footprint: Eliminates external relay panels by integrating relay switching directly into the I/O termination base
- Standardized Wiring: Screw-terminal field wiring with consistent pinout across FLEX I/O TB series — reduces commissioning time and technician training overhead
- Long Service Life: Mechanical relay rated for >10 million operations under rated load conditions
System Architecture & Signal Flow
The 1794-TB3 operates as the field-side termination base for a paired FLEX I/O digital output module. Signal flow is as follows:
- PLC Processor (ControlLogix / CompactLogix / SLC 500) issues output command via backplane or network
- FLEX I/O Adapter (e.g., 1794-AENT, 1794-ADN) receives command and routes to the appropriate I/O module slot
- Digital Output Module drives the relay coil on the 1794-TB3 terminal base
- Relay Contact closes/opens to switch field-side load (motor starter, solenoid valve, indicator lamp, etc.)
- Field Device responds to relay state — status feedback returned to PLC via input module if required
This architecture ensures complete electrical isolation between the 24V DC control logic and field-side AC/DC loads up to 240V AC.
Sourcing & Quality Verification
- Source: Procured from authorized distributors, OEM surplus, and verified secondary market channels
- Inspection Protocol: Each unit undergoes visual inspection, label verification (catalog number, series, date code), and functional bench test prior to shipment
- Authenticity: Counterfeit screening performed — holographic labels, PCB markings, and firmware version cross-referenced against Rockwell Automation documentation
- Condition Options: New-in-box (NIB), factory-refurbished, and tested-used available — condition clearly stated on each order confirmation
- Documentation: Certificate of conformance and test report available upon request for MRO and OEM procurement requirements
Procurement Process
- Submit RFQ — Contact us via support@konmask.com or +0086 19859288691 with quantity, required condition, and delivery timeline
- Receive Quote — Pricing confirmed within 1 business day; volume discounts available for orders of 5+ units
- Order Confirmation — Purchase order or online checkout accepted; proforma invoice issued for wire transfer payments
- Inspection & Dispatch — Unit inspected, photographed, and packed with anti-static protection; tracking number provided within 24 hours of payment clearance
- Delivery — DHL / FedEx / SF Express options; typical transit 3–7 business days international, 1–3 days domestic China
- After-Sales Support — 90-day warranty on tested units; technical support available for integration questions
Technical FAQ
Q: Is the 1794-TB3 compatible with all FLEX I/O digital output modules?
A: The 1794-TB3 is designed for use with specific FLEX I/O relay output modules. Verify module-to-base compatibility using Rockwell Automation’s 1794 Selection Guide (Publication 1794-SG001) before ordering.
Q: Can the relay outputs switch both AC and DC loads?
A: Yes. The Form C relay contacts are rated for both AC (up to 240V AC) and DC (up to 24V DC) loads, subject to current derating per load type. Refer to the module datasheet for full derating curves.
Q: What is the minimum order quantity?
A: Single-unit orders are accepted. Volume pricing applies at 5, 10, and 25+ unit tiers.
Q: Do you provide Rockwell Automation factory warranty?
A: New-in-box units sourced from authorized channels carry the original manufacturer warranty. Tested-used and refurbished units carry Konmask’s 90-day functional warranty.
Q: Can you supply the matching FLEX I/O adapter and power supply?
A: Yes. Konmask stocks a broad range of FLEX I/O ecosystem components including adapters (1794-AENT, 1794-ADN, 1794-ACN15), power supplies, and I/O modules. Contact us for a complete BOM quote.
Q: How do I verify the firmware version or series letter of the unit I receive?
A: Series letter and firmware revision are printed on the module label. Pre-shipment photos are provided upon request. If a specific series revision is required, please specify in your RFQ.
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Contact: support@konmask.com | +0086 19859288691
