FANUCA20B-2901-0982A20B-2901 Plug-In Daughter Module for Series 16 / 18 Model B and C Main Boards — Tested Takeout, Module Only

Product Description

What this part is

A Fanuc A20B-2901-0982, a plug-in module for Fanuc CNC controls. It is catalogued by parts dealers for the Series 16 and 18, Model B and Model C controls, and the numbers around it come from Fanuc’s module rather than rack-card range.

What the A20B-2901 range actually is

This is the most useful thing we can tell you about the number, and it changes how you should think about the part.

Fanuc’s A20B-2900 and A20B-2901 numbers are not full rack boards. They are the modules that mount onto a master or main CPU board — physically small assemblies that plug into sockets on the big board. In the Fanuc Series 16/18 module tables that we could verify, the A20B-2900/2901 range covers PMC CPU modules, PMC engine modules, DRAM modules and SRAM modules: for example A20B-2900-0780 (PMC CPU module for PMC-NA), A20B-2901-0581 (PMC CPU module for PMC-NB), A20B-2900-0790 and A20B-2901-0660 (PMC engine modules), and A20B-2901-0400 / A20B-2901-0402 in the memory-module group.

So the product tier here is a daughter module, not a card. Our previous copy called it a “Circuit Board Module” and said it “provides reliable control and motion capabilities” for “PLC systems” — which is filler, and pointing at PLCs is misleading on a CNC part. If your fault diagnosis has led you to a module on the main board rather than to a card in the rack, this is the right kind of part. If you are looking for a rack card, it is not.

Function — what we are not claiming

We could not find a Fanuc document, or any source we would rely on, that states what the -0982 module specifically does. Its neighbours in the range are CPU, engine, DRAM and SRAM modules, and it is very likely to be one of those — but “very likely” is not a specification, and the difference between a CPU module and an SRAM module is not something a buyer can absorb after delivery. So we state the range’s character and stop there.

One thing worth flagging if it turns out to be a memory module: an SRAM module holds machine data — parameters, part programs, tool offsets, PMC ladder — and is battery-backed. If that is what this is, it arrives blank and your data must be reloaded from your own backup. We make no claim that any data is present on these modules.

Decoding the part number

A20B — Fanuc’s common prefix for surface-mount circuit assemblies used in modern-generation CNC controls. The other prefixes in use are A16B and A17B.2901 — the module group: master-board-mounted modules (PMC CPU, PMC engine, DRAM, SRAM) for the Series 16/18 generation. The adjacent A20B-2900 group serves the same role.0982 — this specific module.
Sibling numbers seen catalogued alongside this one include A20B-2902-0190, A20B-2902-0272 (control board), A20B-2902-0490 (HSSB graphic CRT module) and A20B-2902-0070 (2-axis servo control module). Those are the A20B-2902 group, adjacent but distinct — listed here for orientation, not as substitutes.

Model B and Model C — why the generation matters:
The Series 16 and 18 controls came in successive hardware generations — Model A, then Model B, then Model C — and Fanuc changed the board and module architecture between them. A module for a 16-B or 16-C main board will not fit or function on a 16-A, and vice versa. This module is catalogued for Model B and Model C. Before ordering, confirm your control’s model letter, which appears on the CNC’s nameplate and in its parameter list, not just the series number.

Condition — what “takeout, tested” means here:
These are used modules pulled from equipment and tested. On a Fanuc daughter module, “tested” means it was verified functional on the bench or in a test control — it is not a certification that it will boot your specific machine with your specific software, because on a module carrying CPU or memory function the software and the parameter set are part of the equation. Three units are in stock, which is unusual depth for a tested Fanuc module and means we can offer more than one from the same batch.

What is not included

Module only. Not included: the master or main CPU board it plugs into, the rack and backplane, the memory backup battery, all cabling, the power supply unit, and any Fanuc system software, PMC ladder or machine data.

Interchange guidance

Search forms include A20B-2901-0982, A20B29010982, A20B 2901 0982, A20B2901-0982 and A20B-29010982. Adjacent Fanuc modules for orientation: A20B-2900-0780 and A20B-2901-0581 (PMC CPU modules), A20B-2900-0790 and A20B-2901-0660 (PMC engine modules), A20B-2901-0400 / -0402 (memory modules), A20B-2902-0190, A20B-2902-0272, A20B-2902-0490 and A20B-2902-0070.

Fanuc Corporation remains in business and the Series 16/18 installed base is still substantial and in production, but these modules are no longer supplied new. Module-level repair and identification is handled by the legacy CNC trade — MRO Electric, FanucWorld and Radwell all work on A20B modules and hold documentation that is not public. If you can identify this module’s function from your own parts list or maintenance manual, tell us and we will publish it here with the source credited.