FANUCA20B-3300-0260Plug-In CPU Processor Card with Dual Check Safety for Series 16i / 18i / 20i / 21i CNC

Product Description

What this part is

A Fanuc A20B-3300-0260 CPU card — the plug-in central processor module for Series 16i, 18i, 20i and 21i CNC controls, built around a 486MMX-class processor and carrying Dual Check Safety. It mounts onto the control’s main motherboard (the A20B-8100-013x family of model A cards), not directly into a card rack.

This is a CPU-tier processor card, not an I/O card and not an expansion or option board. Supplied as a bare card.

Decoding the order code

A20B – Fanuc printed-circuit-board prefix. On the i-series controls A20B covers both the motherboards and the plug-in processor, axis and option cards that mount on them.3300 – the control generation group. A20B-3300 is the Fanuc Series 16i / 18i / 20i / 21i plug-in card group. Sibling numbers in the group cover other functions — A20B-3300-0121, for instance, is an axis control card for the same platform.0260 – the specific card, here the CPU with Dual Check Safety./11F – the board edition, or revision level. A revision suffix, not a different part number.

Dual Check Safety: what it actually does:
Dual Check Safety is Fanuc’s safety-rated cross-checking function. Two independent CPUs in the control monitor the commanded and actual speed and position of each motor and compare their results. A disagreement is detected at high speed and power is removed from the motor through two independent paths. That is what makes safe-speed and safe-position functions on the machine possible — a guard-open reduced-speed mode, for example, rather than a hard stop.

The practical consequence for a buyer: if your machine is specified with Dual Check Safety, a non-DCS CPU card will not restore the safety function, and conversely a DCS card on a machine not configured for it will alarm until the corresponding parameters and ladder are in place. Match the card to the machine’s safety specification, not just to the control series.

Published specifications

Function: plug-in CNC central processor card with Dual Check SafetyProcessor: 486MMX-class CPU chipsetPlatform: Fanuc Series 16i, 18i, 20i, 21i CNC controlsMounting: plugs onto the control motherboard, typically the A20B-8100-013x model A cardSafety architecture: two independent CPUs cross-checking speed and position, power removal via two independent paths

What is not included

Card only. This listing does not include the CNC motherboard it plugs onto, the control enclosure or card rack, the CNC power supply, the LCD or CRT display, the operator panel or MDI keyboard, servo or spindle amplifiers, FSSB fibre or servo cables, ribbon or flat cables, connector or terminal-block kits, memory / graphics / I/O plug-in modules, a memory card or CompactFlash, the SRAM backup battery, or any CNC system software, safety parameters, PMC ladder or option-enable codes. Dual Check Safety requires the machine’s safety parameters and ladder to be correctly configured; none of that is supplied with the card.

Quantity and configuration

Sold as 1 piece — one bare CPU card. New old stock, in an opened box.

Installation and setup notes

Back up CNC parameters, PMC ladder and safety parameters before touching the control. Power down, lock out, and allow the supply to bleed down. Handle the card by the edges with a wrist strap. Note the exact position and orientation on the motherboard before removal — the i-series plug-in cards are keyed to specific sockets. Safety-related functions must be re-validated after any change to a Dual Check Safety CPU: verify the safe-speed and safe-position behaviour against the machine builder’s acceptance procedure before returning the machine to production.

Interchange guidance

Searchable equivalents of the same part number: A20B-3300-0260, A20B33000260, A20B 3300 0260, A20B-3300-0260/11F, A20B33000260 11F. Other editions of the same base number are the same card at a different revision level. Adjacent 3300-group numbers such as A20B-3300-0121 or A20B-3300-0360 are different cards — different function, not interchanges.