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

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.

Range coverage: PMC CPU modules, PMC engine modules, DRAM modules and SRAM modules. Examples: 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.

Product tier: daughter module, not a rack card. 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.

SRAM note: an SRAM module in this range holds machine data — parameters, part programs, tool offsets, PMC ladder — and is battery-backed. Machine data should be reloaded from your own backup.

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 catalogued alongside this one: 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 for orientation rather than 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 fits the 16-B and 16-C architecture only. This module is catalogued for Model B and Model C. The control’s model letter appears on the CNC’s nameplate and in its parameter list.

Condition

Condition: used module pulled from equipment and tested. Testing basis: bench or test-control verification that the module is functional. On a module carrying CPU or memory function the software and the parameter set are part of the operating equation.

Quantity and configuration

Module only. The master or main CPU board, rack and backplane, memory backup battery, cabling, power supply unit, and Fanuc system software, PMC ladder and machine data are each separate items.

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, and these modules are supplied from the legacy CNC trade. Module-level repair and identification is handled by that trade — MRO Electric, FanucWorld and Radwell all work on A20B modules.