FANUC Robot Controllers Explained: RJ3, RJ3iB, R-30iA, R-30iB and R-30iB Plus

Published: October 26, 2026

FANUC robot controllers come in generations: R-J2, RJ3, RJ3iB, R-30iA, R-30iB and the R-30iB Plus, the newest in our stock. A used FANUC arm should come with the controller it was set up to run with. Our listings show the controller in the title, so you can match arm and controller before you call.

The Generations, Oldest to Newest

R-J2 and RJ3. Older controllers you will still find on the used market. We keep data sheets for the FANUC R-J2 controller and the FANUC R-J3 controller. In our stock, the RJ3 runs arms like the Arc Mate 120i, the M-16i and the S-500i.

RJ3iB. The next step, and still common in plants. Our R-J3iB controller post covers it. RJ3iB units in our stock include the Arc Mate 100iB, 100iBe and 120iB, the FANUC S-500iB and the M-6iB/6S. We also have a standalone FANUC RJ3iB controller from 2005.

R-30iA. You will also see the R-J3iC name come up alongside it, and our R-J3iC and R-30iA controller post covers both. A lot of our heavy stock runs on it, including the FANUC M-900iA/260L, the M-900iA/400L, the M-410iB/160 palletizing robot and the M-710iC/70.

R-30iB. Comes in more than one cabinet size, which we cover in our post on R-30iB A and B cabinet sizes. R-30iB units in our stock include the Arc Mate 100iC/6L, the M-20iB/25, the M-710iC/50 and the M-2000iA/900L.

R-30iB Plus. The newest controller across our inventory. See our R-30iB Plus controller write up. It runs the Arc Mate 120iD, the M-20iD/25, the M-900iB/360 and the M-2000iA/2300. The smaller R-30iB Mate Plus and R-30iB Compact Plus cabinets show up on our M-20iD/12L and an un-used LR Mate 200iD/7L.

The Arm Name Does Not Tell You the Controller

The same arm can ship on different controllers depending on the year it was built. In our own stock, the M-900iA/350 shows up on the R-30iA from 2013 and on the R-30iB from 2015. The LR Mate 200iD/7L shows up on both the R-30iB and the R-30iB Plus. The M-6iB/6S shows up on both the RJ3iB and the R-30iA. Always check the controller in the listing, not just the arm.

Older Controller or Newer?

An older controller is not a bad buy. Plenty of RJ3iB and R-30iA robots are still running in plants, and if your techs already know them, a matching unit fits right into your spare parts shelf and your training. The trade off is age. Parts for the oldest generations get harder to find every year, and newer equipment on your floor may expect a newer controller on the other end.

A newer controller makes the most sense when you are building a new cell, tying into newer PLCs and vision, or standardizing a line for the long run. For a straight replacement on an existing line, matching the controller you already run is usually the simpler path. Either way, our used FANUC robots listings show the controller in each title so you can sort it out quickly.

What to Check on a Used FANUC Controller

It matches the arm. A controller is set up for a specific arm. The servo amplifiers inside are sized for that robot's motors and the software is configured for that model. Do not assume a controller from one arm will run another.
Software and options. Ask what application software is loaded, such as HandlingTool, ArcTool or SpotTool, and what options came with it. Options you need but do not have are a cost to plan for.
Program backup. If the robot is coming off a working line, ask for a backup of its programs and settings. A FANUC robotics memory card is one way to carry it.
Teach pendant. Confirm the pendant matches the controller generation and comes with the unit. We also have a post on the FANUC tablet teach pendant.
Cables. The robot connection cables run between the arm and the cabinet. Our post on robot connection cables explains what they do, and we carry an RP1 and RM1 extension cable set for the R-30iB Plus.
I/O. Know how the controller will talk to your PLC and safety circuit. See our post on industrial robot I/O. We also have a post on the FANUC ES connection.

Controller Parts We Stock

FANUC servo amplifiers: A06B-6105-H002 from the RJ3iB era and A06B-6114-H302
FANUC I/O modules: modules and racks listed by part number
FANUC robot cable sets: listed by part number

Our post on understanding servo amplifiers covers what the drives inside the cabinet do. The rest of our parts are in the FANUC robot parts category.

Selling Robots or Controllers?

We buy complete robots, spare controllers and parts. Start on our sell your machinery page or ask about robot and controller appraisals.