Start with the manufacturer, not a search engine. Look up the exact part number on the manufacturer’s own product page, read its lifecycle status and the successor it names, then check what differs: footprint, wiring, firmware and software. If the successor does not fit the machine, the original part is usually still for sale as new surplus, refurbished or used.
Is the part really obsolete?
Check the status of the exact article number on the manufacturer’s product page. A dealer’s “obsolete” label is often older or broader than the facts: status is set per article, not per family, so one variant of a range can be discontinued while its neighbour is still active. Note the date you checked it.
The vocabulary differs by manufacturer. Rockwell Automation uses Active, Active Mature, End of Life and Discontinued, and publishes what each one means. Siemens uses PM codes in the “Product Lifecycle (PLM)” field of each product page: PM300 for active, PM400 once the phase-out has started, PM410 once the product is sold only as a spare part. Large changes also come as announcements, such as Siemens’ S7-300 phase-out notice, which dates each milestone and names the successor families.
Where do manufacturers publish the successor?
Most large automation manufacturers name a successor on the discontinued product’s own page or in a published list, and that is the first place to look. Distributor cross-reference tables and forum answers are useful leads, but they copy the manufacturer’s data, sometimes late and sometimes wrongly, so treat them as hints to verify.
- Rockwell Automation. The product page carries a “Replacement Product” field and a replacement category. The page for 22B-D010N104, a PowerFlex 40 drive, shows it discontinued on 30 June 2025, with 25B-D010N104 as an “Engineering Replacement”.
- Siemens. The product page in SiePortal, formerly the Industry Mall, shows the PLM status and, where one exists, a successor. For the KP300 key panel 6AV6647-0AH11-3AX0, in PM410, it names 6AV6647-0AH11-3AX1.
- Schneider Electric. Answers often sit in its FAQ base. FAQ FA305594 names the TM241C24T as the “closest replacement” for the TM238LDD24DT controller.
- Mitsubishi Electric. It publishes discontinued-model lists per series with the recommended replacement and the discontinuation date. The MELSEC-F list maps, for example, the FX3G-14MR/ES, whose production ends in December 2026, to the FX5S-30MR/ES. Omron and other Japanese manufacturers publish similar notices per product.
Is the successor a drop-in replacement?
Rarely. Words such as “engineering replacement” and “closest replacement” mean exactly that: the new part does the same job, but something about it differs and needs engineering time. Mitsubishi’s list says it plainly: programs or wiring may need changes, so read the successor’s manual before you use it. Compare five things before you order:
- Mechanical. Footprint, depth, mounting holes, DIN rail or panel cut-out, and the space for cables.
- Electrical. Supply voltage, terminal layout, I/O count and type, rated current.
- Firmware and software. Whether the project converts, which engineering tool it needs, and whether the old program loads at all.
- Communication. The fieldbus or network port, and whether the controller sees the new part with the same configuration.
- Certification. Safety ratings and approvals belong to a specific article and revision; the safety parts guide explains why a “same model” replacement can lose them.
Treat the swap as an engineering change, not a purchase: test the part, record what changed, and update the drawings and the spare-parts list. The PowerFlex 4 to 525 guide works through one real case.
Suffixes, revisions and look-alike numbers
A replacement search often fails on the last characters of the number. Two numbers that differ only in the final block may be the same article in different packaging, or a different hardware revision with different firmware. A different prefix can mean an environmental variant that costs twice as much. The guide to Siemens order numbers shows where those traps sit in one manufacturer’s scheme, and the same habit works everywhere: read the whole number off the rating plate, not off an old order.
When the successor does not fit
Sometimes the honest answer is that no successor fits without a project you cannot run this year. Then the original part is the replacement. Discontinued automation parts usually stay available for years as new surplus, refurbished or used stock; check the warranty on offer and run the counterfeit checks on any source you have not used before.
Buying the original buys time, not a solution. Use it to plan a last-time buy or a migration on your own schedule, as the obsolescence guide describes. If a part number finds no offers here, a request for quotes can still name it, with the rating-plate text in the note, and reach suppliers who carry that manufacturer.
Sources
Links checked on 13 October 2026.
- Rockwell Automation: product lifecycle status: the definitions of Active, Active Mature, End of Life and Discontinued.
- Rockwell Automation: 22B-D010N104: lifecycle status, discontinued date and the replacement product named on the page.
- Siemens Industry Online Support, entry 109809890: the phase-out announcement for SIMATIC S7-300 and ET 200M, with the PM400 and PM410 dates and the successor families.
- Siemens SiePortal: 6AV6647-0AH11-3AX0: a product page showing a PLM status and its successor.
- Schneider Electric FAQ FA305594: the closest replacement for the TM238LDD24DT.
- Mitsubishi Electric: discontinued MELSEC-F models and replacements (Japanese): discontinued FX models, their dates and recommended replacements.