The FANUC A20B-8001-0630 is a Sub-CPU board for compatible FANUC i-Series Model A CNC controls. It provides additional processing for supported control configurations, including applications requiring a second CNC path and associated axis, spindle and analog-output functions.

This board connects to the control-unit F-BUS backplane through JNA. FANUC documentation identifies CA54 for servo checking, JA41 for a serial spindle or position coder, and JA40 for analog output. It is an additional CPU board, not the CNC's main CPU card.

A20B-8001-0630 Product Information

Sub-CPU and Two-Path Control Function

In a supported multi-path configuration, the Sub-CPU assists with the additional CNC path, axis control and related spindle interfaces. Its exact enabled functions depend on the CNC model, installed software, machine-builder configuration and surrounding control cards.

Compatibility and Slot Checks

Match the complete A20B-8001-0630 number, PCB revision, motherboard, CNC series, option-slot position and software configuration. FANUC states that the board cannot be installed in the center slot of a three-option-slot unit or the slot farthest from the LCD in a four-option-slot unit. Do not substitute a main CPU or later Sub-CPU board solely by appearance.

Testing and Installation Notes

REACO CNC checks the label, PCB condition, connectors, F-BUS recognition, Sub-CPU startup and applicable interfaces on a compatible test system. Back up CNC and Sub-CPU parameters, programs, offsets and PMC data before removal; software restoration may be required. Isolate power and use ESD protection during installation.

Related resources: FANUC PCB boards, FANUC CNC controls and FANUC CNC repair services.