Allen-Bradley 20-COMM-D ControlNet to DPI Adapter

Technical Dossier

Product Details And Specifications

Allen-Bradley 20-COMM Series Technical Notes

The Allen-Bradley 20-COMM series is a family of communication adapter modules designed for integration with PowerFlex 70, 700, 700H, 700S, 700L, and 750-series AC drives via the Drive Peripheral Interface (DPI). These adapters serve as the primary network gateway between Rockwell Automation variable frequency drives and plant-level industrial networks including ControlNet, DeviceNet, EtherNet/IP, PROFIBUS DP, Modbus/TCP, and others.

The Evolution of 20-COMM Architecture

The 20-COMM series was introduced alongside the PowerFlex 70 and 700 platforms in the early 2000s as a modular, hot-swappable peripheral interface solution. The DPI (Drive Peripheral Interface) bus replaced the earlier SCANport interface used on legacy 1336 PLUS and 1336 IMPACT drives, offering higher bandwidth, improved diagnostics, and support for multiple simultaneous peripheral connections.

First-generation 20-COMM adapters (circa 2002–2006) supported single-network connectivity with basic parameter read/write capability. Subsequent firmware revisions introduced explicit messaging, I/O data mapping enhancements, and EDS file support for improved network configuration. The 20-COMM-E (EtherNet/IP) variant emerged as the dominant adapter as plant Ethernet infrastructure matured through the 2010s.

As of 2026, the majority of 20-COMM variants are in the mature-to-declining lifecycle phase. Rockwell Automation has transitioned newer PowerFlex 755T and 6000T platforms to embedded network ports, reducing reliance on external adapters. However, the installed base of PowerFlex 70/700/750 drives remains extensive, sustaining strong demand for 20-COMM spare parts and long-term maintenance support.

20-COMM Full Catalog & Functionalities (SKU List)

Communication Adapters — Network Interface Modules

• 20-COMM-D: ControlNet to DPI adapter; supports scheduled and unscheduled messaging on ControlNet 1.5 networks.
• 20-COMM-E: EtherNet/IP to DPI adapter; 10/100 Mbps, supports explicit and implicit messaging, most widely deployed variant.
• 20-COMM-C: DeviceNet to DPI adapter; Group 2 slave device, supports polled and change-of-state I/O.
• 20-COMM-EB: Dual-port EtherNet/IP adapter with embedded switch; supports Device Level Ring (DLR) topology for high-availability networks.
• 20-COMM-P: PROFIBUS DP to DPI adapter; supports DP-V0 and DP-V1 services, GSD file configuration.
• 20-COMM-M: Modbus/TCP to DPI adapter; supports Modbus function codes FC03, FC06, FC16 for legacy SCADA integration.
• 20-COMM-H: RS-485 HVAC (BACnet MS/TP) to DPI adapter; used in building automation and HVAC drive applications.
• 20-COMM-I: Interbus to DPI adapter; supports Interbus remote bus and local bus configurations.
• 20-COMM-L: LonWorks to DPI adapter; FTT-10A transceiver, used in building management system integration.
• 20-COMM-Q: CANopen to DPI adapter; supports DS402 drive profile for motion-oriented CANopen networks.
• 20-COMM-S: RS-485 SCANport to DPI adapter; legacy bridge for integrating PowerFlex drives into existing SCANport-based control architectures.
• 20-COMM-K: ControlNet coax to DPI adapter; earlier ControlNet variant using RG-6 coaxial media (predecessor to 20-COMM-D).
• 20-COMM-F: Foundation Fieldbus H1 to DPI adapter; used in process automation environments with FF-compliant DCS platforms.
• 20-COMM-G: SERCOS interface to DPI adapter; supports SERCOS II ring topology for coordinated motion applications.
• 20-COMM-ER: EtherNet/IP adapter with fiber optic port option; used in high-EMI or long-distance Ethernet runs in heavy industrial environments.
• 20-COMM-EI: EtherNet/IP isolated adapter variant; provides galvanic isolation for noise-sensitive drive installations.

Sourcing Hard-to-Find & Obsolete 20-COMM Parts

Several 20-COMM variants — including the 20-COMM-K, 20-COMM-L, 20-COMM-I, and 20-COMM-G — have been discontinued by Rockwell Automation with no direct replacement offered. End users operating legacy PowerFlex 70 and 700 drives in long-lifecycle plant environments (refineries, nuclear facilities, municipal water systems) frequently require these adapters for emergency replacement or planned maintenance without full drive replacement.

Quality Control for the 20-COMM Range

Each 20-COMM adapter processed through DriveKNMS undergoes a structured verification protocol prior to shipment:

• DPI Bus Integrity Test: Adapter is connected to a live PowerFlex 700 test drive. DPI communication is verified at full polling rate. Parameter read/write cycles are executed across all standard drive parameter groups.
• Network Protocol Validation: For each adapter variant, the corresponding network protocol is tested using a reference PLC or network analyzer. For 20-COMM-D units, ControlNet scheduled connection establishment and data transfer are verified using a 1756-CNB reference module.
• Firmware Version Verification: Installed firmware is read and compared against Rockwell Automation's published compatibility table for the target drive series. Firmware upgrade is performed where required.
• Isolation and Insulation Check: Electrical isolation between DPI bus and network port is tested per IEC 61010-1 requirements.
• Thermal Cycling: Units flagged as refurbished undergo 4-hour thermal cycling between 0°C and 55°C to screen for latent component failures.
• Final Functional Run: Each unit completes a 30-minute continuous operation test under simulated drive load conditions before packaging.