The Allen-Bradley 1771-ACN, also cataloged as the 1771-ACN I/O Adaptor Module, operates as a dedicated hardware component for high-speed deterministic field communication within Allen-Bradley PLC-5 chassis platforms. It links remote 1771 I/O chassis to a ControlNet cable system, permitting real-time data transfer between the central processor and distributed I/O modules without requiring direct rack placement. The unit manages backplane timing, packet routing, and local power distribution across the internal 1771 backplane structure.

Part Number Breakdown & Configuration Matrix

The 1771-ACN designation defines the explicit functional profile within the 1771 architecture. The prefix "1771" denotes compatibility with the heavy-duty 1771 rack and power supply series. The "ACN" suffix designates ControlNet network adapter functionality. This module connects to coaxial ControlNet media using standard BNC taps, converting network token-pass frames into parallel 1771 backplane read/write commands for local digital, analog, and intelligent block modules.

Core Electrical & Environmental Parameters

Backplane Integration & Deterministic Network Execution

The 1771-ACN leverages high-speed backplane bus communication velocity Licences to maintain continuous synchronicity between field devices and the PLC-5 processor. Operable over EtherNet/IP deterministic networks and ControlNet media, the adapter scales I/O density by mapping multi-rack configurations into single logical image tables. Integrated firmware flash compatibility guarantees seamless protocol synchronization, eliminating packet drops during heavy backplane scanning cycles and preventing I/O updating delays across large-scale industrial installations.

Package Contents & Kit Details

• 1 x Allen-Bradley 1771-ACN ControlNet Adapter Module
• 2 x Plastic chassis keying bands
• 1 x Anti-static protective enclosure packaging
• 1 x Installation insert sheet

Mounting & Mechanical Installation Directives

• Keying Insertion: Place mechanical keying bands on the backplane connector between pins 54-56 (upper slot) and pins 16-18 (lower slot) prior to module insertion to prevent damage.
• Chassis Alignment: Align the card guides of the leftmost slot in the 1771 chassis; slide the module firmly until the top locking latch fully engages with the chassis frame.
• Coaxial Connection: Connect the ControlNet BNC tap directly to the front-panel RG-6 coaxial connector. Ensure a 75-ohm trunk terminator is installed at both physical cable ends.
• Grounding Requirements: Secure the chassis ground wire to the enclosure grounding bus using minimum 14 AWG copper wire to prevent electrical noise interference.

Technical Inquiries & Field Diagnostics

• What is the backplane current demand for the 1771-ACN module?

  The module draws exactly 1.0 A at 5 VDC from the internal 1771 backplane power supply. Ensure total rack current calculation accounts for this load.

• How is physical connector keying established for this adapter?

  Keying is established using plastic keying bands placed on the upper connector at pins 54-56 and lower connector at pins 16-18 inside the chassis slot.

• Can the 1771-ACN be inserted or removed under backplane power?

  No, power to the 1771 I/O chassis backplane must be completely switched off before inserting or removing the module to avoid hardware damage.

• What thermal dissipation must be factored into cabinet cooling?

  The module generates a thermal dissipation rate of 17.06 BTU/hr with a total power dissipation rating of 5 W during normal continuous operation.

• What media type does the 1771-ACN use for network link connection?

  It connects to ControlNet coaxial cable systems using standard RG-6 quad-shield cable and 75-ohm BNC tap connectors attached to the front panel.

• What operating temperature range does the 1771-ACN support?

  The hardware operates within a ambient thermal envelope of 32 to 140 deg F (0 to 60 deg C) and stores between -40 to 185 deg F (-40 to 85 deg C).

• Where is the 1771-ACN module positioned inside the 1771 chassis?

  The 1771-ACN adapter must always be installed in the leftmost slot (Slot 0) of the 1771 I/O chassis to govern backplane communication correctly.

• What is the total weight and shipping dimension for transport planning?

  The module weighs 0.96 kg with estimated shipping dimensions measuring approximately 5 cm x 16.5 cm x 27.4 cm in standard protective packaging.