FANUC MOTN-017 Limit Error: Why the Robot Will Not Jog Out of Joint Mode (Frames, Limits, and the SR-6iA Trap)

You are commissioning a new cell on an SR-6iA with an R-30iB Plus, you switch the teach pendant from joint to world coordinates, and the alarm strip reads MOTN-017 limit error (G:1, A:3). Joint mode jogs fine. World mode does not. Nothing moved physically, nothing was broken, and the operator is convinced the robot is at fault. It is not. MOTN-017 is a software-limits alarm that fires whenever the path the controller computes would push an axis past where it is allowed to go. We see this most often during commissioning, after frame changes, and after offline programs are loaded onto a different cell.

This post is written for technicians and integrators chasing MOTN-017 on M-410iC palletizers, R-30iB welders, R-30iB Plus tending cells, and the SR-6iA scara family. The diagnostic is the same across cabinets, but the frame logic on the SR-6iA catches more first-time programmers than any other model in our service mix.

What this error actually means

MOTN-017 is the motion-software limit alarm. The FANUC error code manual is explicit on page 863: “MOTN-017 Limit error (G:%d^2, A:%s^7) Cause: One or more axes are in violation of the motion software limits. Refer to alarm text for specific group and axis. Remedy: Move or re-teach the taught position. If this error occurred in auto mode, this robot may not be able to resume.” That is the controller telling you a target position, or a path through it, would drive a joint past the upper or lower software limit configured in $PARAM_GROUP.

The PNT1-101 echo on page 1025 reinforces the same idea from the paint-shop side: “PNT1-101 Limit error Cause: The taught position was outside the normal work envelope of the robot. One of the robot axes could not reach the position.” Same alarm, different label, same fix.

Mechanically, every joint has hard mechanical stops, and inside those stops the controller carries an upper and lower software limit. The software limits are tighter on purpose. They protect cables, the dress pack, and adjacent equipment. When you jog or run a program that would exit them, MOTN-017 fires before the robot moves.

Most common causes, in order of probability

In order of how often we land on each one:

1. Joint already at its software limit when the program starts. A jog left the robot parked at J3 +170 degrees, the program then asks for J3 +175, and MOTN-017 fires before the move starts. Common during commissioning and after manual jogging.
2. UFRAME rotated so taught XYZ targets the back of the workspace. A frame edited from offline simulation can flip 180 degrees relative to the running cell. The same x/y target now sits behind the robot, the inverse kinematic solution falls outside joint limits, and you get MOTN-017 on world mode but not joint. The DIY Robotics MOVE TO thread documents this exact pattern (reference thread).
3. World jog cannot find a kinematic solution at the current pose. This is the SR-6iA trap that catches first-time users. Joint mode jogs each axis directly. World mode demands a valid kinematic solution at every step, and an SR-6iA near a singularity or near a joint limit cannot deliver one. A Reddit user described exactly this scenario on an SR-6iA with R-30iB Plus: jog works in joint mode but throws MOTN-017 (G:1, A:3) in world mode (Reddit thread).
4. Software limits tightened during a controlled start. Someone modified $PARAM_GROUP joint limits to protect a fixture, then never opened them back up. The DIY Robotics forum’s standing MOTN-017 thread points operators at POSN > JNT as the first place to confirm joint position against the limit (forum reference).
5. UTOOL mismatch on a loaded program. Less common, but a tool offset that does not match the program will compute a target the robot cannot reach inside its limits.

How to diagnose in under 10 minutes

Step 1. Note the group and axis from the alarm. MOTN-017 always names G: A:. The axis number tells you which joint to look at.

Step 2. On the teach pendant, press POSN, then F2 for JNT. Read the current joint value of the offending axis and compare against the software upper and lower limits in MENU > SETUP > Joint or in $PARAM_GROUP. The DIY Robotics forum confirms this is the first move (forum reference).

Step 3. If the joint is at or past its software limit, jog it back into the working range using joint mode. If the joint is well inside its limit and you still cannot jog in world mode, the problem is the frame or the kinematic solution, not the limit itself.

Step 4. Confirm the active UFRAME and UTOOL on the pendant. Check that the frame the position was taught in matches the frame the program is calling. A frame number mismatch is one of the most common silent causes (MOVE TO thread).

Step 5. If you are on an SR-6iA or LR Mate and only world mode fails, check whether you are near a singularity. The world jog has to maintain orientation, and certain wrist orientations near J5 = 0 will fail with MOTN-017 even though the joints themselves are well inside their limits (Reddit thread).

How to fix it

The fix depends on what the diagnostic surfaced.

If a joint is parked past its software limit: jog it back inside the limit using joint mode, then resume the program. Do not open the limit to clear the alarm.

If the UFRAME is wrong for the loaded program: switch to the correct UFRAME number, or update the program to call the frame it was taught in. Verify by jogging a known taught point and watching the position display.

If the alarm only fires in world mode: jog into a pose where a kinematic solution exists, then try world mode again. On an SR-6iA, that often means moving J3 out of an extreme position before world jog will work.

If the software limit is genuinely tighter than the cycle needs: open the limit only after engineering review. Hardstops exist for a reason, and a customer who lifted J4 limits without checking the dress pack has bought themselves a future failure. Document the change and the reason, back up before and after, and re-test the full cycle.

If a UTOOL is mismatched: change the tool number to match the one the position was taught with, or re-teach the position with the current tool number.

When to call a specialist

Call us when the alarm fires inside the documented work envelope, frames and tools check out, joint positions are clear of their software limits, and MOTN-017 still locks the cell. At that point the conversation is about $PARAM_GROUP limits, mastering accuracy, or kinematic configuration on a specific arm variant. On a production cell, opening joint limits is the kind of change that wants a planned outage and a documented back-out.

Same applies if you inherited a cell with limits set in $PARAM_GROUP by someone who is no longer at the customer site. We can audit and document the limits before the next product change asks the robot to go where the limits do not allow.

contact us for a service call, or set up a maintenance preventive contract so frame and limit changes are reviewed before they generate alarms during production.

Related errors to check

• MOTN-018 Position not reachable: same family. The controller cannot find a kinematic solution at all, where MOTN-017 says the solution is past the limits.
• MOTN-019 In singularity: kinematic-solution alarm. If world-mode jogging on an SR-6iA fails with MOTN-017, MOTN-019 is the next thing to watch for.
• PNT1-101 Limit error: the paint-shop echo of MOTN-017. Same root cause, same fix path.

Probot Systems is a FANUC integrator based in Lévis, Quebec. We commission palletizers, welders, and tending cells across Canada and the US, and frame and limit problems are a recurring item on our commissioning checklist. If your cell is throwing MOTN-017 after a frame edit or an offline-program load, that is a contact us conversation.