Troubleshooting workflows
Diagnosing an Axis Overtravel Fault
A structured workflow for tracing an axis overtravel on a FANUC R-30iB Mate robot, separating a program or soft-limit cause from a hardware limit switch, a shifted mechanical stopper, or a wiring fault. It walks the alarm and status screens, the MANUAL OT Release procedure for both calibrated and uncalibrated robots, and the physical checks that keep the fault from returning. Every menu path, field, and code is drawn from the FANUC operator, maintenance, and alarm manuals.
- Step 1.
Read the exact alarm text and axis number
Press MENU, open the ALARM screen, and select the alarm history screen [4 ALARM]. Press F5, DETAIL to expand the entry and confirm whether it is SRVO-005 Robot overtravel, which means the robot moved beyond a hardware limit switch, or a jogging overtravel violation reported against a software joint range. Note the axis number, since when you jog in JOINT the affected axis is listed in the error log.
- Step 2.
Confirm the condition on the stop signal status screen
Press MENU, select 0 NEXT then 4 STATUS, press F1 [TYPE], and choose Stop Signal. The Overtravel line reads TRUE while any articulation is out of the operation range beyond the overtravel switch, which is also why servo power switched off. This screen tells you the alarm is a live overtravel and not a stale history entry.
- Step 3.
Cross-check the per-axis OT status on the monitor screen
On the STATUS Axis monitor screen, the OT column shows the over travel status as 0 or 1 for each joint. A 1 against a single joint points you at that axis, while all-zeros with a live alarm suggests a signal or wiring issue rather than a true mechanical overtravel. Record the Inpos and torque values here too, since they help later when you decide if the position itself is wrong.
- Step 4.
Understand what the controller has already done
On an SRVO-005 the controller shuts off drive power, applies the robot brakes, lights the operator panel FAULT light, turns on the teach pendant FAULT indicator, and limits motion for the involved axes. Knowing this explains why the robot is dead and why a plain RESET will not move it. It also means recovery requires the deliberate MANUAL OT Release sequence, not a normal alarm clear.
- Step 5.
Determine whether the robot is calibrated
The release path differs for a calibrated (mastered) robot versus an uncalibrated one, so establish this before touching the OT Release screen. A calibrated robot refuses a direct release and requires you to jog out under SHIFT, while an uncalibrated robot can be released field by field. If mastering is in doubt, treat the robot as calibrated and follow the safer jog-out path.
- Step 6.
Inspect the program and taught points near the fault
Open the program at the line that was executing and review the last taught points, plus any tool offset, user frame, or position register that shifts the target. A point that is valid in one frame can drive a joint past its range once an offset or a different frame is applied. Look specifically for a position that legitimately exceeds the axis travel rather than a random stop.
- Step 7.
Check for recent program, frame, or limit changes
Review what changed since the robot last ran this motion without faulting, including edited points, altered frames, new offsets, or a modified axis limit. The manual warns that changing the joint moving range can make an alarm occur at a position that was programmed and ran fine earlier. A single edit is the most common reason a long-stable cell suddenly overtravels.
- Step 8.
Review the joint operating area (soft limits)
Press MENU, select 6 SYSTEM, press F1 [TYPE], and choose Axis Limits to open the SYSTEM Axis Limits screen, which lists AXIS, GROUP, LOWER, and UPPER in degrees. Compare the faulting axis position against its LOWER and UPPER values to see whether the software range, and not a physical switch, was the trip point. Remember the axis range cannot be extended beyond the factory setup, and any change needs a cold start to take effect.
- Step 9.
Open the MANUAL OT Release screen
Press MENU, select SYSTEM, press F1 [TYPE], and choose OT Release. The MANUAL OT Release screen lists each AXIS with an OT MINUS and OT PLUS value, and the overtraveled axis shows TRUE in one of those columns. This confirms both the axis and the direction of the overtravel before you attempt to move off it.
- Step 10.
Release an uncalibrated robot from the screen
If the robot is not calibrated, move the cursor to the TRUE OT PLUS or OT MINUS value of the affected axis and press F2, RELEASE, which should change the value back to FALSE. Then hold SHIFT, press F2 RESET and wait for servo power, select the JOINT coordinate system with COORD, hold the DEADMAN and turn the pendant ON, and jog the axis off the switch. Keep SHIFT held throughout, since releasing it drops servo power and forces you to repeat the steps.
- Step 11.
Release a calibrated robot by jogging out under SHIFT
On a calibrated robot the RELEASE key returns the message Can't Release OT, so press F5 DETAIL to read the instruction to clear the error and jog out. Hold SHIFT and press F2 RESET, wait for servo power, then continuously hold the DEADMAN and turn the pendant ON/OFF switch to ON. Still holding SHIFT, jog the overtraveled axis off the switch at low speed, keeping personnel clear of the arc of travel.
- Step 12.
Jog off in the correct direction at reduced speed
Jog only in the direction that brings the joint back into the movable range, using JOINT coordinates and a low override so the motion is controlled. Watch the OT status flip toward FALSE or 0 as the axis clears the switch. If the axis will not clear even at the mechanical end of travel, stop and suspect a switch, connector, or mechanical stop problem instead of forcing it.
- Step 13.
Inspect the physical limit switch and mechanical stopper
With the axis clear, examine the hardware limit switch and the mechanical stopper for that joint, since the manual requires stoppers to be adjusted to the software settings and used together with limit switches. A shifted, loose, or damaged stop can trip an overtravel at a position that used to be legal, producing a false or premature fault. On a freshly installed robot, remember the J2 and J3 axes rest against the hard stops at shipment and will alarm at first power-on until released.
- Step 14.
Check wiring when the robot is not actually overtraveled
If the axis is inside its range yet SRVO-005 persists, the maintenance manual has you check the EE connector, the RMP1 and RP1 connectors at the robot base for bent or loose pins, and connectors CRF8 and CRM68 on the servo amplifier. Lock out and tag out the controller's power before opening the cabinet or unmating these connectors. Inspect the robot connection cable for cuts, kinks, shorts, or a ground fault along its length. If SRVO-214 for a blown amplifier fuse appears at the same time, check the FS2 fuse on the servo amplifier.
- Step 15.
Verify mastering if the fault position looks wrong
If the overtravel happened at a position that should be well inside the range, confirm the axis mastering data has not drifted before blaming the switch. Lost or shifted mastering moves the controller's idea of zero, so a legal pose can read as out of range. Resolve any mastering loss first, because releasing and re-running against bad mastering can drive the axis somewhere unexpected.
- Step 16.
Rule out look-alike faults from impact detection
An SRVO-006 Hand broken alarm from the safety joint or HBK signal, and an SRVO-050 Collision Detect alarm, can stop the robot in a way that resembles an overtravel but has a different cause. Read the alarm text carefully, since the recovery for a broken safety joint or a collision is not the OT Release procedure. Treat any collision or hand-broken event as a separate investigation into what the tool struck.
- Step 17.
Clear the fault and test at reduced speed
Once the cause is corrected and the axis is back in range, reset the alarm and run the affected motion at a low speed override to confirm it stays inside the limits. Watch the OT status and the axis position through the move rather than trusting a single clean cycle. Return to full speed only after the reduced-speed pass runs clean.
- Step 18.
Document the root cause and corrective action
Record which axis overtraveled, whether the cause was a program or offset error, a soft-limit change, a shifted mechanical stop, a switch, or a wiring fault, and what you did to fix it. Note any connector or fuse you found suspect so a recurrence is easy to trace. A repeated overtravel that keeps getting cleared without a found cause is a warning sign of a developing mechanical or wiring problem.
Common questions
- How long does Diagnosing an Axis Overtravel Fault take?
- Diagnosing an Axis Overtravel Fault is rated Intermediate and takes about 45 minutes across 18 steps.
- What tools do I need?
- You will need Teach pendant, Alarm history and status screens on the pendant, R 30iB Mate maintenance manual for limit switch and connector locations, Alarm code list (B 83284EN 1).
- What should I do before starting?
- Robot stopped safely with the overtravel alarm active and drive power off. Knowledge of whether the robot is currently calibrated (mastered). Access to the SYSTEM and STATUS menus on the pendant.
- What is the first step?
- Read the exact alarm text and axis number. Press MENU, open the ALARM screen, and select the alarm history screen [4 ALARM]. Press F5, DETAIL to expand the entry and confirm whether it is SRVO-005 Robot overtravel, which means the robot moved beyond a hardware limit switch, or a jogging overtravel violation reported against a software joint range. Note the axis number, since when you jog in JOINT the affected axis is listed in the error log.