IS220PDOAH1B Discrete Output Module (PDOA)

"Discrete Output Module" and "PDOA pack" refer to the same GE Speedtronic Mark VIe hardware — the pack that turns controller commands into relay outputs on a discrete output terminal board. This unit ships new surplus, in its original factory packaging. Like every IS220-series pack, it mounts directly on its terminal board rather than sitting in a rack, connecting through a single DC-37 pin connector, and it reaches the <R>, <S>, or <T> controller over the I/O Ethernet network (IONet) through dual RJ-45 ports.

The pack's acquisition board drives and monitors up to 12 relay outputs, reading feedback back from the terminal board. Which relay technology is actually in the circuit depends on the terminal board: electromagnetic relays on TRLYH1B, C, D, and F boards, or solid-state relays on TRLYH1E boards. Power comes in on a 3-pin, 28 V dc connector with soft-start current limiting, and on every power-up the pack disables all outputs until its internal self-tests pass — the enable path is deliberately kept independent of the command path so relays cannot chatter during initialization.

Before You Install This, Rule Out the Terminal Board

• Relay wiring, contacts, fuses, and terminal connections all live on the TRLY-type terminal board — check these first, since they produce the same symptoms as a bad output channel on the pack.
• The swap test is the fastest way to confirm a pack fault: install the suspect pack on a known-good terminal board, or a known-good pack on the suspect board, and see which one the problem follows.
• Don't mistake the power-up self-test sequence — a short period with all outputs disabled — for a hardware defect.
• Confirm the terminal board's relay type before assuming a straight pack swap will resolve an output issue; electromagnetic and solid-state terminal boards are wired differently.
• Check the IONet cabling, connectors, and switch before condemning the pack — network issues and pack failures present identically from the control room.

What the Suffix Means

IS220 marks this as a Mark VIe distributed I/O pack, PDOA the discrete output function, H1 the design generation, and B a hardware or processor revision beyond the original H1A. We have not seen a fully documented list of every functional difference between H1A and H1B for this specific pack, so the safest approach is to treat the suffix and revision as something that must match your terminal board and ControlST project rather than assume interchangeability. Our GE Speedtronic Part Number Decoder explains how GE structures the rest of the number.

Related Packs and Terminal Boards

PDOA pairs with TRLY-family relay terminal boards. If your panel uses a single combined terminal board for both discrete inputs and outputs, look at the related PDIO pack instead. Our GE Mark VI IS200 Boards collection lists compatible terminal boards for cross-reference.

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