GE Fanuc WESDAC D20S Versatile Control Output Module

System Composition

The D20 Status Module consists of two detachable components:

• WESTERM D20 S (Bottom Module – Termination Board)

• WESDAC D20 S (Top Module – Signal Processing & Communication)

The WESTERM D20 S handles all field wiring connections, while the WESDAC D20 S processes input signals and communicates with the main D20 processor (WESDAC D20 M). These modules are mounted together on a standard 19-inch rack and interconnected via three 40-pin connectors.

Key Features

Field Wiring & Termination (WESTERM D20 S)

• Provides compression-type terminals for field connections.

• Supports up to 64 digital inputs, divided into 8 groups of 8.

• Each group has its own common return and is electrically isolated from the others.

• Accepts input voltage ranges from 12 VDC to 130 VDC using voltage-dropping resistors.

• All inputs are bipolar, supporting both positive and negative ground systems.

Surge & Impulse Protection

• Equipped with capacitors and varistors on all field inputs.

• Provides Surge Withstand Capability (SWC) and impulse protection for enhanced reliability in harsh environments.

Flexible Configuration

• Inputs can be set for either group common or contact wetting modes.

• Wetting supply can be internal or sourced externally and is fused for protection.

• Jumper block located on the WESTERM D20 S sets the slave address for the module on the D.20 Link.

Communication & Power

• Features two DB9 connectors for D.20 Link daisy chaining and communication.

• Includes one DB9 maintenance port (WESMAINT D20) for diagnostics and VT100 terminal access.

• Power for the WESDAC D20 S is delivered via the D.20 Link cable and filtered and fused on the WESTERM D20 S.

Field Maintenance-Friendly Design

• Only passive components are housed on the WESTERM D20 S.

• All active components reside on the WESDAC D20 S, allowing for easy replacement of the processing unit without disturbing field wiring.

Distributed I/O Architecture

The GE D20 Remote Terminal Unit (RTU) leverages a distributed processing architecture with real-time data acquisition and control. The system’s modular design allows I/O modules to be positioned close to primary equipment, reducing wiring complexity and improving response times.

Architecture Highlights

• Intelligent I/O Modules:
  Each module includes an onboard microprocessor and acts as a slave device to the D20 main processor.

• Supported Protocols:

• DNP3 Protocol – for industry-standard SCADA communication.

• D.20 Link (HDLC Protocol) – a high-speed, high-level GE proprietary protocol.

• Communication Interfaces:
  Each I/O module is equipped with serial communication ports and a variety of field connection options.

• Modular Hardware Design:
  All remote I/O modules share a common hardware construction, enabling consistency and simplified maintenance across the system.