GE D20 EME

Description

GE D20 EME – Product Overview

Product Description
The GE D20 EME is a legacy, yet highly robust, remote I/O processor module from the GE Fanuc Series 90-30 PLC family. This module, the GE D20 EME, is designed to function as an intelligent Genius I/O Block Controller. Its primary role is to manage a cluster of Genius I/O blocks, handling all data exchange and communication with the central PLC CPU over the high-integrity Genius Bus. When you implement a target GE D20 EME, you create a distributed I/O network that enhances system reliability and reduces wiring complexity. The proven design and deterministic communication of the GE D20 EME have made it a trusted component in countless industrial installations for decades.

Product Parameters

• Part Number: D20 EME (Note: May have suffixes like -001, -002 indicating firmware/revision).
• Product Type: Genius I/O Block Controller / Remote I/O Processor
• Compatible System: GE Fanuc Series 90-30 Programmable Logic Controller (PLC).
• Host Bus Interface: Plugs directly into the Series 90-30 backplane.
• Managed Network: Genius Serial Bus (Token-Passing, 153.6 kbaud).
• Function: Acts as the master controller for up to 30 Genius I/O blocks (discrete, analog, special function) located remotely from the main PLC rack.
• Diagnostics: Provides extensive diagnostic capabilities for both the module itself and the entire Genius I/O network it controls.

Advantages and Features

• Distributed Architecture: Reduces long home-run wiring costs by allowing I/O to be placed close to field devices, with only a single serial cable returning to the controller.
• High Noise Immunity: The Genius Bus protocol and twisted-pair cable are highly resistant to electromagnetic interference (EMI), making it ideal for harsh industrial environments (e.g., near motors, welders).
• Deterministic Performance: Token-passing network ensures predictable and consistent I/O scan times, which is critical for precise control.
• Built-in Diagnostics: Continuously monitors the health of connected Genius blocks, providing clear fault indicators on the module and status data to the CPU for quick troubleshooting.
• Proven Reliability: This is a mature, field-proven technology known for its exceptional long-term stability and mean time between failures (MTBF).

Application Cases in Application Fields
The GE D20 EME was and continues to be used in heavy industrial applications requiring reliable distributed I/O:

• Automotive Manufacturing: Controlling welding robots, paint shop conveyors, and assembly line stations where the PLC is centralized but devices are spread over a large area.
• Water & Wastewater Treatment: Distributing I/O across large plant sites for pump control, valve actuation, and chemical feed systems, connected back to a central control room.
• Material Handling: Managing extensive conveyor networks, sortation systems, and automated storage/retrieval systems (AS/RS) in distribution centers.

Comparisons with Competing Products

• vs. Siemens ET 200 Distributed I/O: Siemens uses PROFIBUS DP or PROFINET. The GE D20 EME‘s Genius Bus is a proprietary, deterministic system often considered more robust in extremely noisy environments than early open-fieldbus systems, though at lower data speeds.
• vs. Allen-Bradley Remote I/O Adapter (1771-ASB): The Allen-Bradley solution uses a proprietary Remote I/O link. The D20 EME is comparable, with each offering deep integration within their respective PLC families (GE vs. Rockwell). The Genius Bus is frequently noted for its simpler configuration and superior diagnostics.
• vs. Modern Ethernet-based I/O (e.g., GE’s VersaMax EIO): Modern systems offer faster data rates and use standard Ethernet cabling. The D20 EME represents a previous generation of technology but remains superior in applications where extreme EMI resistance and deterministic performance are prioritized over raw speed and IT integration.

Selection Suggestions and Precautions

• Selection Suggestion: Choose the GE D20 EME primarily when expanding or maintaining an existing Series 90-30 system with Genius I/O. It is a legacy part, so for new greenfield projects, modern Ethernet-based solutions from GE (PACSystems) are strongly recommended.
• Precautions:
  1. Legacy & Obsolescence: This is a discontinued product. Availability is from surplus/refurbished channels. Ensure you have a long-term sparing strategy or a migration plan.
  2. Software Requirement: Configuration of the Genius network and the D20 EME requires older GE Fanuc programming software (VersaPro, PME, or LogicMaster).
  3. Bus Termination & Rules: The Genius Bus must be properly terminated at both physical ends of the daisy chain. Exceeding the maximum cable length (depending on baud rate) or the maximum number of drops (30) will cause network failure.
  4. Firmware Matching: The firmware revision of the D20 EME should be compatible with the Series 90-30 CPU’s firmware and the Genius I/O blocks on the network.

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