Sun StorageTek SL8500 Modular Library System
 

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In this Document

Purpose

Troubleshooting Steps

References

Oracle Confidential PARTNER - Available to partners (SUN).
Reason: Confidential for service personnel

Applies to:

Purpose

SL8500 - How to Troubleshoot "Servo Mech Track Event" Errors.

Troubleshooting Steps

The SL8500 rails are laid out in an oval pattern like a race track.    There is an upper ("track") and a lower ("s-track") robot track assembly that attaches the handbot to a rail.   Each robot assembly has a motor that enables the handbot to travel along this geared track.  The distance traveled along the track is measured in tachs (gear rotations)  or mils (1000 mils = 1 inch)  units. 

Theoretically these two motors should always be aligned.  When the two motors get misaligned but the alignment positions are within tolerance limits,  5010 or 5070 error is sent from the robot controller.
-- Error 5010 means "An excessive position error was detected during motion". 
-- Error 5070 means "Exceeded maximum allowed position error between the track motors. Possible gear slip occurred".

The handbot travels along the rail at a high rate of speed but needs to have a controlled stop whenever it reaches its target.  Certain events could cause the handbot to fail to stop within the allowable stopping range
in front of its target device or cell.  If this happens,  5002, 5015 or 5016 error is sent from the robot controller.
-- Error 5002 means "Mechanism traveled outside of it's stoplock range"
-- Error 5015 means "The mechanism has fallen outside the allowable stoplock range"
-- Error 5016 means "The mechanism was unable to settle into the desired stoplock window"

The handbot can also fail due to the servo motor trying to compensate for missed service intervals while moving along the track.  This could be due to a problem with track alignment or may indicate a very busy controller that is not able to service the interrupt signals from the motors within the allotted time.   The controller may send an error message regarding a low voltage condition that may not necessarily indicate a power issue per se but more of a power surge to compensate for a stalling robot.
-- Error 5051 means "A low voltage condition has been detected on the servo motor power"
-- Error 5069 means "The max or min current was requested an excessive amount of times during a stall move with a minimum position not reached"
-- Error 5080 means "Mech failed to hit an End Stop on a Zero Count on Stall move (stall abort). Tach counter not zeroed."
 
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From the "servo mech track" error messages in the Error Warn Info Eventlog, determine if the problem is being reported on the same area along the track.   List down the mils values on each message and verify if the values point to a particular track area.  If so,   perform any or all of the following actions:

    1.  Inspect the track along the specified area

    2.  Perform track alignment check using the time bot
         Refer to SL8500 - How to Resolve Rack Track - Rail Issues on Library (Doc ID 1306064.1)

    3.  Perform bot perpendicularity check using the time bot
         Refer to SL8500 - How to Resolve Rack Track - Rail Issues on Library (Doc ID 1306064.1)

    4.  Perform channel gap measurements

    5.  Check for debris along the track

    6.  Perform bot straightness check
         Refer to the HBOT Straightness Test attached to this document.
         The bot straightness test would require assistance from an L2 tape support engineer.

If  track issue found, fix the problem accordingly.


If the "servo mech track" errors occur at random points along the track,  do the following actions:
    1.  Make sure that the drop off cells are empty
    2.  Make sure that there is no tape stuck in the robot's gripper.  (Most of the time, if the drop off cell is full, and there is a tape in the robot's gripper when a reset is requested, the robot initialization will fail.)
    3.  Run diagnostic tests on the robot.  Replace the robot if it fails the tests.
    4.  If "missed interrupt service interval" messages are found in the EWI log, inspect bot brushes
    5.  Run the CLI command, 'stats network'.  If it shows excessive errors in HBC to bot communication, inspect bot brushes and terminators.

If there is no problem found with the track nor with the robot, review the library log snapshot and check for HBB and HBC errors.  If errors are found, verify if such errors are fixed in the latest library code.
 
 

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