The MSG 501 panel hangs, no keys respond, and the alarm display shows 5138 FSSB: AXIS SETTING NOT COMPLETE together with 100: PARAMETER WRITE ENABLE. The fault appeared after replacing the original A20B-2100-0260/09C control card with revision A20B-2100-0260/11d on an A068B-6096-H304 three-axis drive.
Stop repeating the wrong fixes
Start here. Treat the card change as the triggering event. The old revision operated; the replacement revision hangs while the FSSB axis setup remains incomplete.
| Symptom or attempted fix | What it means |
|---|---|
Set the drive's S1/S2 terminator jumper again |
A missing or incorrect terminator can disrupt the FSSB physical link, but the setting was already completed without changing the symptom. Repeating it wastes time unless the bus layout or last-device position is wrong. |
Clear alarm 100
|
This alarm reports that parameter writing is enabled. That is not the FSSB axis-setting fault. Disable parameter writing after configuration work; do not treat alarm 100 as the cause of 5138. |
Reload 9090r.mem repeatedly |
The supplied file must be loaded through the specified service procedure and followed by axis-setting validation. Repeating the transfer without checking the resulting FSSB map does not prove that the map was accepted or retained. |
Assume 11d is equivalent because the base card number matches |
The common A20B-2100-0260 number identifies the card family, but the revision changed from 09C to 11d. Configuration, compatibility, or initialization must be checked before condemning the drive hardware. |
Read the two alarms separately
5138 FSSB: AXIS SETTING NOT COMPLETE means the control has not completed the logical assignment between controlled axes and devices detected on the FSSB chain. The control may see hardware on the bus yet still lack an accepted axis-to-amplifier map.
100: PARAMETER WRITE ENABLE is an operating-state alarm. It appears while parameter changes are permitted. It often remains visible during service work and should disappear after parameter writing is disabled through the control's normal setting procedure.
The frozen keypad changes the diagnostic path. If the screen and keys stop updating before you can reach the FSSB setting display, use the approved startup or service-loading path for this control. Do not cycle power repeatedly while a file write or parameter save could be active.
Confirm the FSSB chain before changing data
Check the physical layer once. A valid logical setup cannot compensate for a broken fiber path, swapped connection, unpowered amplifier, or termination placed on the wrong device.
- Record the displayed alarms and the point in startup at which the keys stop responding.
- Record the installed order of every FSSB-connected device. Match the physical three-axis arrangement to the control documentation rather than relying on axis labels alone.
- With power removed under the machine's electrical service procedure, inspect FSSB connectors, cable seating, cable routing, and drive control-card seating.
- Verify that
S1/S2matches the documented position for the final device in the actual chain. A jumper fitted to a device that is not physically last is still an incorrect termination. - Restore power and check whether all expected drive devices indicate a normal communication state before enabling servo motion.
If a device is missing from the chain, repair that physical fault first. If every expected device is present but 5138 remains, move to axis assignment and retained configuration.
Rebuild the axis setting in a controlled order
Keep the machine inhibited from motion until the logical axis order matches the physical amplifiers. An incorrect assignment can command the wrong motor when an axis is selected.
- Back up the current parameters and service data if the control remains responsive. Preserve the existing file before overwriting any retained configuration.
- Use the old
A20B-2100-0260/09Ccard as an A/B test if it is serviceable. If the control starts normally with09Cand fails again with11d, focus on revision compatibility, initialization, and transferred data. - Install
A20B-2100-0260/11dand verify its seating, FSSB connections, and terminator position. - Load
9090r.memonly through the loading procedure supplied for the MSG 501/FANUC configuration. Confirm that the operation reports completion before cycling power. - Enable parameter writing through the approved control setting. Alarm
100can remain present during this step. - Open the FSSB axis-setting or maintenance function and perform the manufacturer-defined axis assignment for the detected three-axis drive chain. Compare detected device order with the recorded physical order before accepting it.
- Save or accept the assignment using the control's prompted procedure. Perform any requested controlled restart.
- Disable parameter writing. Confirm that alarm
100clears after the setting is returned to its normal state.
If the panel freezes before the axis-setting function becomes available, do not guess parameter values. Capture the last responsive screen and determine whether the approved memory-loading or maintenance startup path can reach the FSSB setup without completing the normal machine boot.
Verify the repair before releasing motion
- Cold-start the control and confirm that the keys remain responsive through the point where the hang previously occurred.
- Confirm that
5138no longer appears and that parameter write enable has been turned off, clearing100. - Review the FSSB diagnostic display. Every installed device must be present in the expected chain position, with one logical assignment for each controlled axis.
- Keep rapid motion and automatic operation disabled. Test one axis at a time at restricted speed while observing the commanded axis, actual motor, direction, feedback, and limit state.
- Restart the control again. A repair is not complete if the axis map works only until the next power cycle.
If 5138 returns after a restart, the assignment was not stored, the wrong data set was loaded, or the replacement revision is not accepting the required configuration. If the panel hangs at the same startup point with the physical chain verified, stop treating termination as the primary suspect.
Avoid the recurring service traps
- Do not change multiple jumpers, files, and parameters in one attempt. You lose the ability to identify which action changed the fault.
- Do not leave parameter writing enabled after service. Alarm
100is the reminder that the control remains in a configuration-change state. - Do not infer axis order from the number of connected devices. FSSB discovery and machine-axis assignment are separate checks.
- Do not command motion immediately after rebuilding the map. First prove that each displayed axis selects the intended amplifier and motor.
- Do not treat matching base card numbers as proof of drop-in compatibility. Record both complete revisions:
A20B-2100-0260/09CandA20B-2100-0260/11d. - Do not substitute an unverified memory file for
9090r.mem. Configuration data must match the machine and control arrangement.
FAQ
What happens if FSSB error 5138 remains after setting S1 and S2?
Verify device discovery and rebuild the logical axis assignment. Correct termination cannot clear an incomplete or unaccepted axis-to-amplifier map.
What happens if alarm 100 stays on after loading 9090r.mem?
Parameter writing is still enabled or the setting has not been returned to its normal state. Disable parameter writing after saving the FSSB configuration, then perform the prescribed restart.
What happens if the MSG 501 hangs before the axis-setting screen opens?
Use the approved maintenance or memory-loading startup path and capture where normal boot stops. Do not guess parameters or continue repeated power cycles while configuration storage may be active.
Stop when the keypad remains locked, the detected FSSB order does not match the physical chain, or 5138 returns after a saved setup and controlled restart. Escalate to official FANUC or Mori Seiki support with the complete card revisions, drive identifier, alarm text, device order, S1/S2 state, and the result of loading 9090r.mem.