IS220PDIAH1A REV. B: Discrete Contact Input Pack

The IS220PDIAH1A is the contact input pack in GE's Speedtronic Mark VIe distributed I/O system, documented in GE's GEH-6721 Mark VIe Control System Guide. It mounts directly on a discrete input terminal board via a single DC-37 pin connector and exchanges data with the <R>, <S>, or <T> controller over the I/O Ethernet network (IONet) through dual RJ-45 ports. A processor board common to every Mark VIe I/O pack pairs with an acquisition board built specifically for contact-input duty.

PDIA reads up to 24 contact inputs plus terminal-board-specific feedback signals, accepting three different input voltage levels depending on which terminal board is installed (TBCIH1, H2, or H3), with a separate path for the isolated, voltage-sensing TICI board. Compatible terminal boards are TBCI, TICI, and STCI — not the DIN-rail mounted DTCI board. Each input runs through a comparator with a variable threshold, is opto-isolated from the control logic through its own isolated supply (though inputs are not isolated from each other), and includes filtering, hysteresis, and its own yellow status LED — lit when the input is picked up, off when dropped out. Optical isolation is rated to 1500 V, the hardware input filter is 4 ms, and the pack is rated for -40 to +70°C operation.

A Real Case Worth Knowing Before You Replace a PDIA

A documented field report on a Mark VIe PDIA pack described intermittent loss of communications: alarms would appear, sometimes clear on their own, with a hardware watchdog fault message, and the pack itself showed no visible problem — Ethernet activity lights were normal and no diagnostic alarms were present at the module when checked locally. The site replaced Ethernet switches, cables, and the PDIA pack itself, and the problem still came and went. Only after swapping the pack onto a different terminal board did the real answer emerge: the fault stayed with the terminal board, not the pack. A brand-new pack alone would not have solved it.

• Separate Process Alarms (bad field values) from Diagnostic Alarms (hardware/comms faults) — they point to different causes.
• Confirm your configuration — Simplex, Dual, or TMR — before troubleshooting, since the expected behavior differs.
• Swap the pack to another terminal board (or a known-good pack onto the suspect board) and see whether the fault follows the pack or stays put. This single test would have saved the pack replacement in the case above.
• Inspect every IONet cable end and connector for corrosion or discoloration, and check cable bend radius against spec.
• Heat, dust, and humidity are widely reported as the leading cause of Mark VIe I/O pack failures generally — packs stacked in vertical columns run hottest at the top, so cabinet airflow is worth checking alongside the hardware.

Reading IS220PDIAH1A REV. B

IS220 marks a Mark VIe distributed I/O pack, PDIA the discrete/contact input function, H1 the design generation, A the hardware revision, and REV. B the board revision within this part number. All of it needs to match your terminal board and ControlST project. Our GE Speedtronic Part Number Decoder explains how the rest of the string is built.

Related Packs and Terminal Boards

PDIA pairs with TBCI/TICI/STCI-family contact input terminal boards. Where a panel needs discrete outputs instead, or both input and output combined, the related packs are PDOA and PDIO respectively. See our GE Mark VI IS200 Boards collection for compatible terminal boards.

What to Include in Your Quote Request

• Full part number with suffix and revision (IS220PDIAH1A REV. B)
• A photo of the label
• Turbine model and Mark control generation
• Quantity
• Urgency of the request

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General Information about the Product
Part Number	IS220PDIAH1A Mark VI IS220
Description	GE General Electric IS220PDIAH1A REV. B I/O Pack Mark VI
Condition	used Cleaned and Tested. With 1 Year Warranty.