Allen-Bradley 1785-KA PLC 5 Communication Adapter Module

The Allen-Bradley 1785-KA, also cataloged as the 1785-KA Communication Adapter Module, operates as a dedicated hardware component for distributed network communication management within PLC-5 platforms.

Hardware Specifications

Industrial Control & Drive Integration

The 1785-KA manages protocol packet translation routines synchronized with the backplane bus communication velocity limitations of the legacy 1771 rack chassis. The module executes frame processing and token pass controls to establish deterministic routing fields, allowing data linking between standard physical channels and higher-tier Profinet / EtherNet/IP deterministic networks via network gateway adapters. Verifying firmware flash compatibility across the local PLC-5 processor block, remote scanner addresses, and peer nodes is required to prevent packet frame collision and maintain continuous memory register mapping across expansive I/O density scaling topologies.

Frequently Asked Questions

Q: Does the 1785-KA communication module support Removal and Insertion Under Power (RIUP)?

A: No. The PLC-5 1771 architecture backplane does not feature hot-swapping protection circuitry. Main power to the chassis assembly must be completely isolated and turned off prior to installing or removing the module to prevent digital transceiver damage or corruption of active data links.

Q: How is the physical hardware addressed within the PLC-5 system network?

A: Node addressing and network parameter definitions for the Data Highway / Data Highway Plus interfaces are established via configuration of the hardware DIP switches located on the side panel of the module housing before insertion into the chassis slot.

Field Installation Guidelines

• Chassis Slot Insertion: Disconnect all power from the 1771 chassis. Slide the 1785-KA module into the designated slot, matching the top and bottom circuit card edge guides, and press firmly until the module locks completely into the backplane connectors.
• Shield Grounding Protocols: All Data Highway and Data Highway Plus cables (such as 1770-CD) must have their insulation shields terminated correctly at the ground terminals using the 1771-WN wiring arm block to suppress high-frequency electromagnetic noise injection.
• Network Line Termination: Install standard physical termination resistors across the signal lines at both physical ends of the completed DH+ network trunk line. This is necessary to stop signal reflection and maintain voltage wave shapes across the data link.