IS220PDOAH1B: Used, Cleaned, and Tested Discrete Output Pack

This IS220PDOAH1B is a pulled used unit that has been cleaned and functionally tested ahead of sale, backed by a 1-year warranty. It's the discrete output pack (PDOA) in GE's Speedtronic Mark VIe distributed I/O system — the half of a discrete I/O chain that turns controller commands into relay outputs. The pack mounts directly on a discrete output terminal board through a single DC-37 pin connector and communicates with the <R>, <S>, or <T> controller over the I/O Ethernet network (IONet) using dual RJ-45 ports.

A processor board shared across all Mark VIe I/O packs pairs with an acquisition board built for relay control: up to 12 relay outputs, with feedback read back from the terminal board. The relay technology in play depends on which terminal board is installed — electromagnetic relays on TRLYH1B, C, D, and F boards, solid-state relays on TRLYH1E boards. Power comes in through a 3-pin, 28 V dc connector with soft-start current limiting, and the pack runs a self-test on every power-up, holding outputs disabled until it passes — a fail-safe measure built into the design, not a sign of trouble.

What to Check Before You Assume the Pack Failed

• Relay contacts, fuses, and field wiring on the terminal board are common causes of an output that won't behave correctly — check these before the pack.
• The swap test resolves ambiguity fast: put the suspect pack on a known-good terminal board (or a known-good pack on the suspect board) and see which one the fault follows.
• Don't mistake the pack's power-up self-test — a brief period with all outputs disabled — for a hardware fault.
• Confirm which relay type the terminal board actually uses before assuming a straightforward pack swap will fix an output issue.
• Check the IONet path — cabling, connectors, switch health — since a network problem can look exactly like a dead pack from the control room.
• In TMR systems, confirm which core is alarming before pulling any one pack from an otherwise healthy triad.

Understanding IS220PDOAH1B

IS220 identifies a Mark VIe distributed I/O pack, PDOA the discrete output function, H1 the design generation, and B a hardware/processor revision. Confirm the full string, including revision, against your terminal board and ControlST project before ordering. Our GE Speedtronic Part Number Decoder covers how the rest of GE's Speedtronic numbering works.

Related Packs and Terminal Boards

PDOA pairs with TRLY-family relay terminal boards. If your terminal board combines discrete input and output in one assembly instead, look at the related PDIO pack. Our GE Mark VI IS200 Boards collection lists compatible terminal boards and neighboring packs.

Information to Include in Your Quote Request

• Full part number with suffix (IS220PDOAH1B)
• A photo of the label
• Turbine model and Mark control generation
• Quantity
• Urgency — planned outage or unplanned downtime

We respond to every quote request within 24 hours, ship worldwide DDP, and accept purchase orders. Pricing isn't posted online — Request a Quote and our team will confirm stock and terms directly with you.