Description
The GE IS420YDOAS1B (commonly designated as the YDOA pack) is a compact, high-reliability Discrete Output I/O Pack manufactured by General Electric for Speedtronic™ Mark VIe and Mark VIeS turbine control and safety instrumented systems (SIS). The YDOAS1B pack mounts directly onto terminal boards (such as the SRLY or TRLY relay output terminal boards) and provides the local processing, internal bus communication, and drive signals required to control up to 12 discrete relay outputs.
Key Specifications & Identification
| Attribute | Details |
| Manufacturer | General Electric (GE / GE Vernova) |
| Model / Ordering P/N | IS420YDOAS1B / IS420YDOA |
| Functional Revision | S1B (Group 1, Revision B) |
| System Architecture | GE Speedtronic™ Mark VIe / Mark VIeS Control Platform |
| Module Type | Discrete / Relay Output I/O Processing Pack |
| Channel Capacity | 12 Discrete Output Channels |
| IONet Ethernet Ports | Dual 10/100 Mbps RJ-45 Ethernet ports (ENET1, ENET2) |
| Compatible Terminal Boards | IS410SRLYS2A, IS200TRLYH1B, IS200TRLYH1F, DREB |
| Operating Power | 28 V DC nominal (supplied through terminal board connector) |
Primary System Functions
- Distributed Output Processing: Executes local signal processing and output commands received from central Mark VIe controllers over dual Ethernet IONet links.
- Direct Terminal Board Integration: Plugs directly onto multi-pin D-sub connectors on compatible terminal boards (like SRLY), eliminating long internal ribbon cables and reducing cabinet wiring complexity.
- Dual IONet Redundancy: Features twin Ethernet interfaces (ENET1 / ENET2) to establish redundant communications with
<R>,<S>, or<T>control networks for uninterrupted signal delivery. - Health & Output Diagnostics: Continuously monitors internal processor health, communication status, supply voltages, and coil driver states, transmitting real-time alarms and status feedback to ToolboxST software.
Servicing & Installation Guidelines
- Hot-Swap Capability in Redundant Configurations: When installed on redundant terminal boards, the IS420YDOAS1B pack can be hot-swapped under power without shutting down the system; verify that output logic latches will not drop field relays unexpectedly.
- Electrostatic Discharge (ESD) Protection: Integrated processing units and Ethernet physical layer (PHY) chips are static-sensitive. Always wear a grounded anti-static wrist strap when handling or replacing the I/O pack.
- Secure Latching & Fasteners: Hand-tighten the mounting screws on the sides of the pack to lock the D-sub interface securely onto the terminal board, preventing signal interruption from panel vibration.
- ToolboxST Configuration & Auto-Reconfiguration: When replacing a pack, ToolboxST can automatically download parameter files and firmware to the new IS420YDOAS1B unit if Auto-Reconfiguration is enabled in the controller hardware settings.
