Allen-Bradley 1794-ACNR ControlNet Adapter for Flex I/O System

1794-ACNR Redundant ControlNet Adapter – Flex I/O Communication Module

The 1794-ACNR is a ControlNet communication adapter for the Flex I/O system. It provides dual redundant ControlNet ports for high‑availability networks. This DIN‑rail module connects up to eight (8) Flex I/O digital, analog, or specialty modules. It exchanges I/O data with controllers over ControlNet at 5 Mbps. The adapter requires an external 24V DC supply (19.2‑31.2V) and draws 400 mA max. It includes diagnostic LEDs for I/O and communication status.

Technical Specifications – 1794-ACNR

• Brand: Allen‑Bradley / Rockwell Automation
• Model: 1794-ACNR (Catalog No. 1794-ACNR)
• Series: Flex I/O – distributed modular I/O system
• Communication Protocol: ControlNet (V 1.25), redundant media
• Data Rate: 5 Mbps per port
• Ports: Two (2) ControlNet BNC connectors
• Max I/O Modules: Up to 8 Flex I/O modules
• Input Voltage: 19.2‑31.2V DC (nominal 24V)
• Current Draw: 400 mA max from external supply
• Flexbus Output: 640 mA @ 5V DC
• Power Dissipation: 4.6 W max @ 19.2V
• Thermal Dissipation: 15.7 BTU/hr @ 19.2V
• Inrush Current: 23A for 2 ms
• Isolation Voltage: 850V DC (basic insulation)
• Operating Temperature: -20…55 °C (-4…131 °F)
• Storage Temperature: -40…85 °C
• Humidity: 5‑95 % non‑condensing
• Vibration (operating): 5 g @ 10‑500 Hz
• Shock (operating): 30 g (IEC 60068‑2‑27)
• Mounting: DIN rail or panel mount
• Enclosure: Open‑type (IP20, requires cabinet)
• LED Indicators: Comm A (red/grn), Comm B (red/grn), I/O status (red/grn)
• Dimensions: 3.7 x 3.6 x 3.4 in (94 x 91 x 86 mm)
• Certifications: CE, UL, cULus, ATEX (Zone 2), marine (ABS, DNV‑GL)

Compatible Equipment – Flex I/O System

• 1794‑IB16 (16‑point digital input)
• 1794‑OB16 (16‑point digital output)
• 1794‑IE8 (8‑channel analog input)
• 1794‑OE4 (4‑channel analog output)
• 1794‑IRT8 (RTD/thermocouple input)
• 1794‑IF4I (isolated analog input)
• Any 1794 series I/O module (up to 8 per adapter)

Oiltech Controls’s Insight – Why This Adapter?

• Redundancy built‑in: Dual ControlNet ports enable media redundancy without extra hardware.
• Proven reliability: Common in PLC‑5 and ControlLogix systems requiring high‑availability I/O.
• Fast data exchange: 5 Mbps deterministic communication suits time‑critical processes.
• Wide temperature range: -20…55 °C operation – suitable for harsh industrial environments.
• Simple diagnostics: LED status for each port and I/O bus simplifies troubleshooting.

Typical Applications

• Oil & gas pipeline monitoring and control
• Power generation distributed I/O
• Chemical plant process automation
• Water/wastewater treatment SCADA
• Material handling and conveyor systems

Installation & Commissioning Notes

• Mounting: DIN‑rail (35 mm) or panel mount. Use proper enclosure due to open type.
• Cabling: Belden RG‑6/U ControlNet cable (3.31 mm² / 12 AWG stranded max).
• Power: External 24V supply must be SELV/PELV rated (CE LVD compliant).
• Addressing: Set node address via DIP switches before power‑up.
• Module count: Max 8 I/O modules – plan system layout accordingly.

5 Professional FAQs – Expert Guidance

• Q: Can I use 1794‑ACNR with ControlLogix L7x controllers?
  A: Yes, it is fully compatible with ControlLogix and CompactLogix via ControlNet bridge modules (e.g., 1756‑CNB). Ensure firmware revision matches.
• Q: What is the maximum cable length for ControlNet with this adapter?
  A: Total trunk length up to 1000 m (3280 ft) with repeaters; point‑to‑point up to 300 m. Use Belden RG‑6/U and proper terminators.
• Q: Does it support I/O module hot‑swap?
  A: No, 1794‑ACNR does not support hot‑swap. Remove power before replacing modules.
• Q: What power supply rating do I need for a full 8‑module system?
  A: The adapter draws 400 mA; each module adds its own current. Calculate total Flexbus + external load. Use at least 24V, 4A supply for typical configurations.
• Q: How do I verify redundant media operation?
  A: Check both Comm A and Comm B LEDs – steady green indicates active link. Use RSNetWorx to monitor media status and configure scheduled/unscheduled data.

Why Buy From Oiltech Controls?

• 15+ years supplying industrial automation spares worldwide.
• Global shipping via FedEx, UPS, or DHL – 24‑28 hour dispatch.
• Every unit is tested (surplus or refurbished) before shipment.
• 12‑month warranty on all modules.
• Technical verification and configuration support for obsolete systems.
• Direct contact: info@oiltechcontrols.com or +86 158 8020 0923 (WhatsApp).

Shipping: FedEx, UPS, DHL – tracking provided. Warranty: 12 months. Packaging: Anti‑static bag, protective foam, installation guide.

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