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| Place of Origin | JAPAN |
| Brand Name | FANUC |
| Certification | CE ROHS |
| Model Number | A16B-3200-0450 |
Part Number: A16B-3200-0450
Manufacturer: FANUC Corporation (Japan)
Product Type: Main CPU Printed Circuit Board
Board Series: A16B-3200
Application: FANUC CNC controllers and robot controllers (including LR-Mate)
Function: Core processor board — integrates CPU module, axis card, FROM/SRAM module
Interface: F-BUS backplane
Variant Note: Without DC converter
The A16B-3200-0450 is the main CPU printed circuit board for FANUC's CNC and robot controller platforms. In the A16B-3200 series — FANUC's family of main processor boards covering multiple CNC and robot controller generations — this board functions as the central processing unit that coordinates all controller operations. Program execution, PMC logic, memory management, servo and spindle communication, and the operator interface all pass through the main CPU board.
In robot controller applications, the A16B-3200-0450 is particularly associated with the FANUC LR-Mate series — the compact tabletop robots widely used for assembly, material handling, and precision machine tending in manufacturing environments.
The board integrates the CPU module, the axis control card, and the FROM/SRAM memory module within a unified assembly, providing the complete processing core for the controller.
The F-BUS backplane interface connects this main board to the other boards in the controller rack.
Power option boards, I/O boards, additional axis cards, and communication boards plug into the backplane and communicate with the main CPU through the F-BUS.
The backplane distributes power, address, and data signals across all installed boards.
| Parameter | Value |
|---|---|
| Part Number | A16B-3200-0450 |
| Manufacturer | FANUC Corporation |
| Product Type | Main CPU PCB |
| Board Series | A16B-3200 |
| Application | CNC controllers, FANUC robot controllers (LR-Mate) |
| Backplane Interface | F-BUS |
| Integrated Modules | CPU module, axis card, FROM/SRAM |
| Variant | Without DC converter |
| Origin | Japan |
| Operating Temperature | 0 – 40°C |
| Storage Temperature | −20 – 60°C |
| Condition Available | New (surplus) / Refurbished / Repaired |
In FANUC's CNC and robot controller architecture, the main CPU board is the highest-level processing component. It is the board that runs the CNC operating system, the PMC (Programmable Machine Controller) ladder logic, and all the higher-level functions that make the controller useful: program interpretation, interpolation, operator display management, communication with external systems.
The main CPU board does not directly interface with the servo drives or the machine's field wiring in most configurations.
It operates at the signal processing and logic level. The servo commands from the CPU board travel to the servo amplifiers through the axis control circuits — in the case of the A16B-3200-0450, the axis card is integrated into the board assembly.
The field I/O — machine inputs and outputs — passes through dedicated I/O boards in the controller rack.
This architectural separation means that main CPU board faults produce high-level system alarms rather than hardware-specific drive or I/O alarms.
A failed main CPU board typically prevents the controller from starting up at all, or causes the startup sequence to halt with a CPU error or system error alarm.
The A16B-3200-0450's integration of the FROM/SRAM module and axis card into the main board assembly is an architectural characteristic shared with several FANUC controller generations designed for compact or embedded applications.
The FROM (Flash ROM) stores the CNC or robot controller's operating software — the system software that the controller loads at power-on.
The SRAM stores parameters, program data, and other data that must persist when power is removed but needs to be writable during operation.
This SRAM is battery-backed; the battery maintains data during power-off. The axis card provides the servo interface for the controller's controlled axes.
In the LR-Mate robot context, this integrated assembly gives the compact controller its full processing capability in a minimal physical footprint — appropriate for the LR-Mate's design intent as a small, space-efficient robot for densely packed manufacturing environments.
FANUC's LR-Mate robots are among the most widely deployed compact industrial robots in the world.
The LR-Mate series is used extensively for machine tending, assembly, inspection, and material handling in automotive, electronics, food processing, and precision manufacturing.
The controller that directs these robots depends on the main CPU board to execute the robot's motion programs, process sensor inputs, and manage the robot's six servo axes.
When the A16B-3200-0450 fails in an LR-Mate controller, the robot stops.
The impact on production depends entirely on what the robot was doing — for a machine tending application feeding a CNC machine tool, the CNC machine also stops for want of part loading and unloading.
Getting the main CPU board replaced quickly is directly connected to minimising the production impact of the failure.
Q1: The FANUC controller shows an alarm at power-on that indicates a CPU error or system initialisation failure. The controller cannot complete its startup sequence. Is this the main CPU board?
A CPU error or system init failure alarm at startup is consistent with a main CPU board fault, but it can also be caused by a failed memory module (FROM or SRAM), a power supply delivering incorrect voltages to the board, or a backplane connector issue.
Before concluding the main CPU board has failed, verify the power supply voltages to the board and check all backplane connectors.
If power and connections are confirmed good, the main CPU board or its integrated memory modules are the fault location.
Q2: The controller's SRAM data was lost during a power failure. After power restoration, all parameters must be reloaded. Is the A16B-3200-0450 at fault?
Data loss during a power failure is a battery failure issue, not a main CPU board failure.
The SRAM battery that protects the A16B-3200-0450's parameter data has been exhausted. Replace the battery, reload all parameters from backup, and restore normal operation.
The board itself is not at fault. Establish a regular battery replacement schedule based on the battery's rated service life to prevent recurrence.
Q3: A replacement A16B-3200-0450 was obtained. After installation, the controller starts but the robot does not move correctly — some axes have incorrect positions. What is happening?
Incorrect axis positions after a board replacement are almost certainly a parameter issue. The replacement board's FROM and SRAM start in their factory-default state.
All robot-specific parameters — axis calibration data, robot model configuration, payload settings, and system parameters — must be loaded before the robot can operate correctly. Restore all parameters from backup.
If a complete backup was not available, the robot will require re-calibration to establish correct axis home positions.
Q4: The LR-Mate robot controller is 12 years old. The main CPU board shows intermittent communication errors between the main board and the servo amplifiers. What should be investigated?
Intermittent servo communication errors on an aging main CPU board point to electrolytic capacitor degradation in the board's power supply section or signal conditioning circuits. The communication timing becomes marginal when supply voltages have excessive ripple.
Check the backplane connector contacts — oxidation on these contacts can also cause intermittent communication errors. If connector cleaning does not resolve the problem, a board refurbishment (capacitor replacement) or board replacement is appropriate.
Q5: Can the A16B-3200-0450 be used in any FANUC CNC controller of the A16B-3200 series, or is it limited to specific models?
The A16B-3200 series contains main CPU boards for different FANUC controller generations, each optimised for its specific processor architecture, memory configuration, and backplane protocol.
The A16B-3200-0450 serves the controller models for which it was designed — primarily the LR-Mate robot controller and compatible CNC applications.
It cannot be substituted for main CPU boards with different part numbers in the series, even if the physical connector appears compatible.
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