Process Control & HART Instrumentation Solution — Allen-Bradley 1794-OE8H/B | FLEX I/O
The Allen-Bradley 1794-OE8H/B is an 8-channel HART-enabled analog output module designed for the FLEX I/O platform. It delivers precision 4–20 mA signals with simultaneous HART communication, enabling engineers to integrate smart field instruments into process control architectures without additional wiring infrastructure.
Where This Product Is Used
The 1794-OE8H/B is specified across demanding process industries where HART-capable field devices must be driven and monitored from a single I/O node:
- Oil & Gas — Control valve positioners, flow control loops, and wellhead automation panels requiring HART diagnostics.
- Chemical & Petrochemical — Reactor temperature and pressure control with smart transmitter feedback via HART pass-through.
- Water & Wastewater Treatment — Dosing pump control and variable-speed drive setpoint delivery with remote device diagnostics.
- Pharmaceutical Manufacturing — FDA-regulated batch processes requiring validated analog output with instrument health monitoring.
- Power Generation — Turbine governor control and boiler feed systems where HART device status is critical for predictive maintenance.
- Food & Beverage — CIP/SIP-compatible process loops with hygienic instrument integration.
Technical Specifications
- Part Number: 1794-OE8H/B
- Series: Allen-Bradley FLEX I/O
- Output Channels: 8 (individually configurable)
- Output Signal: 4–20 mA current loop
- HART Protocol: HART 5 / HART 6 compatible (simultaneous on all channels)
- Resolution: 16-bit DAC
- Accuracy: ±0.1% of full scale at 25°C
- Load Impedance: 0–750 Ω per channel
- Operating Temperature: 0°C to +60°C (32°F to 140°F)
- Storage Temperature: −40°C to +85°C
- Power Consumption: 130 mA @ 5 VDC (from backplane)
- Backplane Compatibility: 1794 FLEX I/O adapter (1794-AENT, 1794-ACN15, 1794-ACNR15, etc.)
- Isolation: Channel-to-backplane isolation
- Dimensions (H × W × D): 94 mm × 23 mm × 87 mm
- Weight: Approx. 0.15 kg
- Certifications: UL, CE, C-Tick
Why Engineers Specify This Model
- Simultaneous HART + Analog Output — No multiplexer required; HART communication runs concurrently with the 4–20 mA control signal on every channel.
- High Channel Density — 8 outputs in a single 23 mm wide FLEX I/O slot minimizes panel footprint in space-constrained enclosures.
- 16-Bit Resolution — Delivers fine-grained setpoint control critical for precision dosing, valve positioning, and speed regulation.
- Predictive Maintenance Ready — HART device variables (PV, SV, TV, QV) are accessible via the controller for condition-based maintenance programs.
- Seamless Studio 5000 Integration — Native Add-On Profile (AOP) support simplifies configuration in Logix Designer without custom programming.
- Proven Field Reliability — /B revision incorporates hardware improvements addressing early-revision field feedback; preferred for new installations.
Complete System Bill of Materials
A typical FLEX I/O HART output node requires the following components:
- 1794-OE8H/B — HART Analog Output Module (this item)
- 1794-AENT — EtherNet/IP Adapter (or 1794-ACN15 for ControlNet)
- 1794-TB3 or 1794-TB3S — Terminal Base (screw or spring clamp)
- 1794-PS13 — Power Supply (if local 24 VDC bus power is required)
- 1756-L8x ControlLogix or 1769-L3x CompactLogix — Host Controller
- HART-capable field instruments (control valves, I/P converters, smart actuators)
- Shielded twisted-pair cable (per HART FSK specification)
Compliance & Industry Standards
- HART Protocol: HART Communication Foundation (FieldComm Group) compliant
- Safety: UL Listed (UL 508); CE Marked (EMC Directive 2014/30/EU, LVD 2014/35/EU)
- EMC: IEC 61000-4 series immunity; EN 55011 emissions
- Industrial Protocols: Compatible with EtherNet/IP, ControlNet, DeviceNet via FLEX I/O adapter selection
- RoHS: Compliant
- ATEX / IECEx: Not rated for hazardous area — use appropriate barriers for Zone 1/2 installations
Quality Assurance & Sourcing
At Konmask.com, every 1794-OE8H/B unit is subject to our multi-point sourcing and verification process:
- Sourced from authorized distributors and verified surplus channels with documented chain of custody.
- Physical inspection: label authenticity, revision marking (/B), connector condition, and housing integrity.
- Functional bench test available upon request for high-volume orders.
- Original manufacturer packaging preserved where available; anti-static packaging used for all shipments.
- Traceability documentation (lot code, date code) provided on request.
How to Source This Part
- In Stock: Add to cart and check out directly — most orders ship within 1–3 business days.
- Bulk / Project Quantity: Contact us at support@konmask.com for volume pricing and lead-time commitment.
- Urgent Requirement: Call or WhatsApp +0086 19859288691 for same-day quotation and expedited dispatch.
- International Orders: We ship globally via DHL, FedEx, and UPS with full export documentation (commercial invoice, packing list, COO).
- Cannot Find Your Part? Send us your full BOM — we specialize in sourcing complete Allen-Bradley FLEX I/O system builds.
Application-Specific FAQ
- Q: Can the 1794-OE8H/B communicate with HART 7 devices?
- A: The module is certified for HART 5 and HART 6. HART 7 devices are backward-compatible and will operate in HART 5/6 mode; however, HART 7-exclusive features (e.g., wireless gateway commands) are not supported.
- Q: Does each channel support independent HART polling?
- A: Yes. All 8 channels support simultaneous, independent HART communication. The host controller can poll each channel’s HART device variables without interrupting analog output.
- Q: What terminal base is required?
- A: The 1794-OE8H/B requires a 1794-TB3 (screw terminal) or 1794-TB3S (spring clamp) terminal base. The terminal base must be ordered separately.
- Q: Is this module compatible with ControlLogix and CompactLogix?
- A: Yes, via the appropriate FLEX I/O adapter (e.g., 1794-AENT for EtherNet/IP). The module is controller-agnostic at the I/O level.
- Q: What is the difference between /A and /B revision?
- A: The /B revision incorporates hardware reliability improvements. Rockwell Automation recommends /B for all new designs. Functionally, both revisions are software-compatible.
- Q: Can I use this module in a hazardous area (Zone 1)?
- A: The 1794-OE8H/B is not ATEX/IECEx rated. For Zone 1 or Zone 2 installations, use certified Zener barriers or galvanic isolators between the module and field instruments.
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