Allen-Bradley 1797-ACNR15 Flex Ex Redundant ControlNet Adapter

Configured for ControlNet communication in hazardous locations, the Allen-Bradley 1797-ACNR15 (1797-ACNR15 ControlNet Adapter) provides direct physical/electrical execution. This hardware unit functions as a redundant ControlNet adapter for the Flex Ex I/O platform, supporting 5 Mbps communication rates and providing intrinsically safe connectivity for up to eight I/O modules within Class I, Division 1 environments.

Hardware Specifications

Industrial Control and Drives Technical Characteristics

The 1797-ACNR15 utilizes redundant ControlNet ports to maintain network availability in demanding control applications. Deterministic communication is achieved via the ControlNet V 1.5 protocol, ensuring consistent data throughput to the host controller. Proper I/O density scaling is managed by the adapter's ability to host up to 8 I/O modules; users must verify that total backplane current consumption does not exceed the adapter's power distribution limits. Firmware flash compatibility is mandatory between the adapter and the ControlNet scanner to prevent bus scheduling conflicts and ensure correct I/O image table mapping.

Frequently Asked Questions

Q: Does the 1797-ACNR15 support hot-swapping?

A: No. Due to its certification for use in hazardous (Class I, Division 1) areas, this adapter module is not intended for insertion or removal while the ControlNet bus is energized. Power must be removed and the area verified as safe before module maintenance.

Q: What are the specific requirements for the ControlNet coaxial cabling?

A: The adapter requires RG-6 quad-shield coaxial cable (part number 1786-RG6 or 1786-RG6F/A). Ensure all connections utilize high-quality BNC connectors and that the network is properly terminated with 75 Ohm resistors to maintain signal integrity at 5 Mbps.

Field Installation Guidelines

• DIN-Rail Mounting: Secure the adapter to a 35 mm DIN rail. Ensure the module is firmly locked in position to withstand the specified 2 g vibration rating during plant operation.
• Intrinsically Safe Wiring: Route all intrinsically safe (IS) signal wiring separate from non-IS wiring. Maintain required clearances as specified by local hazardous area installation codes (e.g., NEC or IEC standards).
• Grounding and Shielding: Bond the Flex Ex chassis to a certified earth ground point. Use the designated shield terminals to ground coaxial cable shields at the entry point of the hazardous zone, ensuring the ground path has low impedance.
• Thermal Management: While the module supports a wide operating temperature range (-20 to 70 deg C), ensure the control enclosure provides sufficient airflow. Avoid mounting the adapter directly above heat-dissipating components to prevent thermal derating.