IS220PDOAH1B / H1BE Discrete Output I/O Pack

This new surplus, factory-packaged unit is labeled IS220PDOAH1B with a further BE suffix variant on GE's own documentation. Rather than guess at what that extra letter changes, our recommendation is straightforward: match the complete part number and revision on the label of the unit you're replacing, and send us a photo if you're not sure — we'll confirm fit before you order.

What's well established is the pack's job: PDOA is the discrete output pack in the Mark VIe (and Mark VIeS) distributed I/O system, mounted directly on a discrete output terminal board through a single DC-37 pin connector, and linked to the <R>, <S>, or <T> controller over IONet via dual RJ-45 Ethernet ports. It drives up to 12 relay outputs and reads feedback from the terminal board, with the installed terminal board determining whether electromagnetic relays (TRLYH1B, C, D, F) or solid-state relays (TRLYH1E) are actually switching the field circuit. A 3-pin power connector with soft-start current limiting handles the 28 V dc supply, and the pack holds all outputs disabled during its power-up self-test sequence as a deliberate safety measure.

Diagnose the Real Fault First

• Check the terminal board before the pack: relay contacts, fuses, and field wiring on the TRLY board produce the same symptoms as a bad output on the PDOA itself.
• Run the swap test — suspect pack on a known-good terminal board, or known-good pack on the suspect board — and see which one the fault follows before ordering.
• A short period of disabled outputs right after power-up is the pack completing its self-test, not a failure.
• Confirm the terminal board's relay type before assuming a pack swap is the answer; electromagnetic and solid-state boards behave differently.
• Check IONet cabling and switch health — a lost network path and a dead pack look identical from the operator screen.

What the Label Tells You

IS220 identifies a Mark VIe distributed I/O pack, PDOA the discrete output function, H1 the design generation, and B (plus any further trailing letter, like the E seen on this label) a hardware or processor revision. Confirm the entire string against your terminal board and ControlST project rather than assuming any PDOAH1-family pack is a blind swap for another. Our GE Speedtronic Part Number Decoder covers how GE builds these part numbers.

Related Hardware

PDOA mounts on TRLY-family relay terminal boards. For a combined input/output terminal board, the related PDIO pack does both jobs in one assembly. Our GE Mark VI IS200 Boards collection covers compatible terminal boards.

What to Send for a Quote

• The complete part number and every suffix letter as printed
• A photo of the label
• Turbine model and Mark control generation
• Quantity
• Timeline for the request

We answer every quote request within 24 hours, ship worldwide DDP, and accept purchase orders. Request a Quote and our team will confirm exact fit and availability with you directly — no prices are posted on the site.