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| Place of Origin | Japan |
| Brand Name | FANUC |
| Certification | CE RoHS |
| Model Number | A20B-8001-0121 |
The FANUC System R-J2 (order designation A05B-2368-B002) is a robot controller from FANUC's R-J2 generation — a controller series designed for FANUC industrial robots across a broad range of payloads and configurations. The R-J2 succeeded the earlier R-J series and was widely deployed in automotive, general manufacturing, and materials handling installations.
The A20B-8001-0121/04B was originally fitted in this specific controller type. The controller's confirmed serial number (E98201519) and hardware type (A05B-2368-B002) provide full traceability for this board back to its original installation — important when sourcing replacement boards for an installed R-J2 system.
| Parameter | Value |
|---|---|
| Part Number | A20B-8001-0121/04B |
| Revision | /04B |
| Board Type | A-B RIO PCB |
| Host System | FANUC R-J2 (A05B-2368-B002) |
| Category | FANUC Robot PCB |
| Application | Industrial robot controller |
FANUC board part numbers carry revision suffixes that identify hardware iterations within the same functional specification. The /04B revision suffix indicates a specific hardware generation of the A20B-8001-0121 board — one with minor component updates or PCB layout modifications compared to earlier revisions such as /01A, /02A, or /03A.
When sourcing a replacement for a failed A20B-8001-0121 board from an R-J2 controller, matching the revision number (/04B) provides the closest hardware match. In most FANUC board families, later revisions are backward compatible within the same system generation, but confirm compatibility from the R-J2 controller's maintenance documentation if an exact /04B revision is unavailable.
R-J2 robot controller I/O fault: A FANUC R-J2 robot controller develops an I/O communication alarm. Robot motion is inhibited pending fault clearance. After confirming the I/O wiring and field devices are intact, the A20B-8001-0121/04B is identified as the failed board. Replacement restores the robot's I/O communication and clears the alarm.
Robot controller refurbishment: An R-J2 robot controller (A05B-2368-B002) is refurbished for continued service. The A20B-8001-0121/04B is replaced as part of a board-level refresh alongside other PCBs in the controller, restoring all boards to a known-good state.
Q1: Is the A20B-8001-0121/04B specific to the A05B-2368-B002 R-J2 variant?
The confirmed installation source is the A05B-2368-B002 (FANUC System R-J2). Whether the A20B-8001-0121 is used in other R-J2 variants depends on the specific controller configuration. FANUC R-J2 controllers came in multiple configurations with different board complements. Verify the board is required for the specific R-J2 variant by cross-referencing the spare parts list for the target controller type.
Q2: What does the serial number E98201519 indicate about this board?
The serial number E98201519 is the R-J2 controller system serial number — the identity number of the complete controller unit from which this board was removed. It confirms the board's installation history and allows traceability to the original FANUC robot system. For replacement orders, the system type (A05B-2368-B002) is more relevant for compatibility confirmation than the individual serial number.
Q3: What alarms does an A20B-8001-0121 failure cause in the R-J2 controller?
A failure of the robot RIO PCB typically generates I/O communication alarms or SVAL (servo alarm) codes related to I/O signal loss. The robot's teach pendant will display alarm codes that identify the I/O link or I/O module as the fault source. Since robot motion interlocks depend on I/O status signals, the robot will typically stop or refuse to operate until the I/O board fault is resolved.
Q4: Can the R-J2 controller operate with a missing or failed A20B-8001-0121?
No. The robot I/O board is a required component for normal controller operation. Without a functional RIO PCB, the controller cannot process I/O signals — the robot cannot receive safety circuit status, end-effector feedback, or external machine interface signals. The robot will remain in alarm state and motion will be inhibited until the board is replaced and I/O communication is restored.
Q5: What data backup is needed before replacing the A20B-8001-0121/04B?
The RIO PCB is a hardware interface board and does not typically store robot programmes or system parameters. However, before any R-J2 controller maintenance, back up the complete robot programme and system variable data via the teach pendant's backup function. This protects robot programmes, coordinate system settings, and I/O assignments if any other board-level event occurs during the maintenance.
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