Allen-Bradley I/O Catalog-Number Decoder

How It Works

1. Type the catalog number

   Enter the code from the module label or BOM, for example 1756-IB16 or 1734-OB8E. The tool uppercases, trims spaces, and strips a single leading A-B or AB- vendor tag, so 'A-B 1769-IQ16' and '1769-iq16' both resolve. Or click one of the example buttons to see a known decode.

2. Read the catalog-number breakdown

   The colored strip splits the code into its segments: bulletin, module type, point/channel count, and feature suffix. Each chip shows the raw characters and what that piece means, so you can see exactly where the count and the suffix come from.

3. Check the decode status before you trust the spec

   A 'Confirmed against a cited Rockwell row' (verified-row) result means the point count, voltage, and feature came from a specific Rockwell table. A 'Decoded from the catalog grammar' (in-grammar) result means the structure is valid but the exact voltage/signal rating was not asserted. Treat the second as a starting point, not a spec sheet.

4. Read the identity card and field notes

   The identity card lists family, type, direction, points or channels, signal class, and any feature. The field-notes block restates the boundary: what the tool identified and what it deliberately did not (chassis power, wiring fit, firmware, safety approval).

5. Handle a flagged code

   If the code is invalid or recognized-but-needs-source, the flag panel says which segment failed (unknown bulletin, impossible count, illegal suffix) or that a legacy SLC / communication row is not yet cached. The tool does not fabricate a spec to fill the gap.

6. Export or verify against the source

   Export the decode to PDF or CSV for the work order, then confirm the point count, voltage range, and revision against the cited Rockwell selection guide or technical-data sheet and the physical module label before you specify, order, or replace anything.

Built For

• Spot-checking a spare on the shelf: type 1756-OB16E to confirm it is a ControlLogix 16-point DC output with electronically protected (fused) outputs before you carry it to the panel.
• Reading a BOM during a panel build: enter 1769-IQ16 and 1769-OB16 to confirm they are Compact I/O 16-point DC input and output modules, not their 1756 lookalikes.
• Catching a typo or a fake part: 1769-IB16 comes back invalid because the 1769 family uses IQ for DC inputs, so you know the line item is wrong before you order it.
• Sorting POINT I/O on a remote rack: decode 1734-IB8 and 1734-OB8E to separate the 8-point DC input bases from the electronically protected 8-point DC output bases.
• Telling a comms card from an I/O card on a drawing: enter 1756-EN2T and the tool reports an EtherNet/IP communication module with no point count, so you do not chase a phantom input wire.
• Triaging a legacy SLC 500 cabinet: 1746-IB16 is recognized as a legacy module but flagged needs-source, a clear signal to pull the count and voltage from the 1747-SG001 guide rather than guess.
• Identifying an analog card: decode 1756-IF8 or 1769-IF4 to confirm channel count (8 and 4) for an analog input module while noting the signal range still needs to come from the technical-data row.

Features & Capabilities

Verified-row versus in-grammar status

Every decode is labeled by how much of it is sourced. A verified-row result carries a point/channel count and voltage taken from a cited Rockwell row; an in-grammar result decodes the structure but withholds the exact rating instead of inventing it.

Invalid-first gating

The parser rejects nonsense before it can masquerade as a product. An unknown bulletin, an unlisted module-type class, an impossible count, a zero-padded count, and an illegal suffix all return invalid with the offending segment named.

Family-scoped grammar

The same letters do not mean the same thing in every bulletin. The 1769 Compact I/O family uses IQ for DC inputs, so the decoder refuses a 1769-IB code rather than borrow the 1756 ControlLogix meaning across families.

Controllers and comms carry no I/O count

Communication modules and controllers do not inherit the I/O point grammar. The decoder identifies them and explicitly returns no point or channel count, and notes that the I in EtherNet/IP is a network name, not an input.

Assumptions

• Grammar and rows come from Rockwell Automation bulletin selection guides (1756-SG002, 1769-SG003, 1734-SG001) and I/O technical data (1756-TD002, 1769-TD006); the exact PDF revisions and page/table numbers are still to be pinned.
• A point or channel count and voltage are asserted only where a cited Rockwell row backs the exact catalog number; a legal-grammar code with no cached row is decoded structurally as in-grammar with the spec marked needs-source.
• Letter-class meanings (IA, IB, OB, IF, OW, etc.) are validated against the documented Rockwell naming convention; classes with no verified row (IC, IG, OX) are recognized but their exact electrical meaning is treated as needs-source.
• The E suffix asserts electronically-protected output only on OB outputs and on verified rows (1756-OB16E, 1734-OB8E); on an input or analog module E is treated as a row-specific variant and flagged needs-source.
• Legacy SLC 500 modules (1746/1747) are recognized by bulletin but returned needs-source until the exact 1747-SG001 rows are cached; their count and voltage are never fabricated.
• The 1756-OB16E output range (10 to 31.2 V DC) was independently re-verified at build against Rockwell's published spec.
• Input is normalized: uppercased, whitespace trimmed, and a single leading A-B or AB- vendor tag stripped before the bulletin-dash-body split.

Limitations

• Identification only. It does NOT confirm chassis power budget, slot/backplane fit, wiring-arm or terminal-base compatibility, firmware or hardware revision, functional-safety (SIL) approval, or replacement equivalence.
• It does not assert a voltage or signal range for an in-grammar decode; only verified rows carry a rating, and even some verified analog rows (1756-IF8, 1769-IF4) leave the signal range to the technical-data table.
• Scope is limited to bulletins 1756, 1769, 1734, and legacy 1746/1747; other bulletins (for example 1791 Block I/O) are rejected as out of scope, not decoded.
• The cached verified-row set is a small representative launch set, not the full catalog; many real sibling modules decode as in-grammar (structure only) rather than verified-row.
• Legacy SLC 500 (1746/1747) codes return needs-source with no count or voltage until those rows are cached, so the tool cannot fully spec an SLC module today.
• It does not check product availability or lifecycle status; Rockwell can supersede or retire a module the decoder still recognizes by grammar.
• It does not decode every option, accessory, conformal-coat (K) or extended-temperature (XT) suffix to a confirmed spec; those suffixes are recognized but needs-source without a cached suffixed row.

References

• Rockwell Automation, ControlLogix System Selection Guide, publication 1756-SG002 (communication-module and platform context; exact revision/page to be pinned).
• Rockwell Automation, 1756 ControlLogix I/O Modules Specifications Technical Data, publication 1756-TD002 (digital and analog I/O row authority; 1756-OB16E output range 10 to 31.2 V DC independently re-verified).
• Rockwell Automation, 1769 Compact I/O Modules Specifications Technical Data, publication 1769-TD006 (1769 I/O row authority; IQ DC-input convention).
• Rockwell Automation, CompactLogix 5370 Controllers Selection Guide, publication 1769-SG003 (1769 controller and Compact I/O selection context).
• Rockwell Automation, POINT I/O and ArmorPOINT I/O Selection Guide, publication 1734-SG001 (1734 grammar and 1734-IB8 / 1734-OB8E rows).
• Rockwell Automation, SLC 500 Modular Hardware Style Selection Guide, publication 1747-SG001 (legacy 1746/1747 context; SLC rows not yet cached, treated as needs-source).

Frequently Asked Questions