Fanuc CPU Board A20B-3300-0472 A2OB-33OO-O472 A20B33000472

A20B-3300-0472 | FANUC A6 CPU Module — 128MB SDRAM / Series 30i / Plug-In Processor Card

Series 30i — The High-End Platform This Card Serves

The FANUC Series 30i sits at the top of FANUC's i-generation CNC product family — a platform built for the most demanding machining applications. While the 0i-D handles standard machine tools and the 31i/32i handle moderately complex multi-axis machines, the 30i is designed for:

Maximum axis count: Up to 40 controlled axes across 10 control paths — enabling fully automated flexible manufacturing cells, multi-spindle transfer lines, and parallel-processing compound machines.

High-speed cutting: AI Contour Control II (AICC II), nano interpolation, and HRV4 high-response current control combine to support high-speed die and mould machining and

aerospace component contouring at speeds that would cause following errors on lower-specification CNCs.

Compound machine capability: Simultaneous mill-turn operations, synchronised multi-spindle turning, and inter-path coordination allow a single 30i CNC to replace what previously required two or more separate CNCs.

The A20B-3300-0472 is the CPU module that powers this platform — the processor card installed on the 30i's main CPU board that executes the CNC's real-time control programme.

Key Specifications

128MB SDRAM — Working Memory for a 40-Axis System

The 128MB SDRAM on the A20B-3300-0472 is the working memory available to the 30i's real-time processing environment. In a 40-axis, 10-path configuration, the CNC must simultaneously maintain:

• Position data and interpolation calculations for 40 axes
• Servo command queues for all active axes across all paths
• PMC ladder execution context for multiple paths
• Programme look-ahead buffer data for all active paths
• System software, option software, and their runtime data

128MB represents a substantial working memory allocation compared to earlier CNC generations. Without adequate working memory, the 30i's look-ahead buffering would be constrained — limiting the maximum feedrate at which the CNC can execute complex contoured tool paths without deceleration.

Application Scenarios

30i CNC CPU module fault: A FANUC 30i machining centre develops system alarm codes pointing to the CPU card. All axis functions are inhibited. After confirming the main board, memory modules, and power supply are intact, the A20B-3300-0472 is replaced. The CNC resumes normal operation.

Robot controller CPU module: The A20B-3300-0472 also serves FANUC robot controllers that use the same main board hardware. The note to back up "Fanuc Robot datas stored into the memory modules" before replacement applies to robot controller applications as much as CNC applications.

FAQ

Q1: Does the A20B-3300-0472 contain any CNC-specific software?

No. CNC system software is stored in the FROM modules — separate plug-in items. The A20B-3300-0472 is the processing hardware only: its SDRAM is working memory that the CPU uses at runtime, not persistent storage. Replacing the A20B-3300-0472 does not affect the FROM content or the SRAM-stored parameters, provided those modules remain intact.

Q2: What data backup is essential before replacing the A20B-3300-0472 in a 30i system?

Back up all parameter data and programme data for all active control paths — in a multi-path 30i system, this means parameters and programmes for each path are backed up separately. Also back up all tool data, work coordinate data, and PMC ladder and data. In a robot application, back up all robot programmes and system variables. Perform the backup before any board handling.

Q3: How does the A20B-3300-0472 (A6 type) compare to the A20B-3300-0475 (A3 type) in terms of performance?

Both are 128MB DRAM CPU modules in the A20B-3300 family, but for different CNC generations and main board types:

• A20B-3300-0475 (A3 type): For 0i-D systems (entry/mid-range i-series)
• A20B-3300-0472 (A6 type): For Series 30i (high-end multi-axis i-series)

The A6 type targets a higher-performance CNC platform with greater axis count, more control paths, and more demanding real-time processing requirements. They are not interchangeable.

Q4: What happens if the 128MB SDRAM on the A20B-3300-0472 fails partially?

Partial memory failure — where some memory cells are faulty but the module still partially initialises — typically manifests as intermittent system alarms, unexplained CNC resets, or corrupted display content. These symptoms can resemble other faults. A full, persistent memory failure causes the CNC to fail its power-on self-test and prevents normal startup. In both cases, replacing the A20B-3300-0472 resolves the memory fault.

Q5: Can the A20B-3300-0472 be tested before installation?

The A20B-3300-0472 requires the host main board to function — it cannot be tested in isolation. The conventional approach is to install the replacement module in the CNC, power up, observe the boot sequence, and confirm the system reaches normal operating state. A module that is suspected to be faulty (from a known-bad source) can be tested by substituting it in a working 30i system if one is available.