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Need help to understand amplier faults


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Hello all,


I hope the forum can point me in a logical direction to better understand amplifier faults. I apologize in advance for my ignorance regarding motion control. I appreciate all inputs.


What variables should I track to best understand amplier errors?


I support Friction Stir Weld (FSW) machines that use GeoBrick GBL6-CO-5F2-10S (with Turbo PMAC) to control five (5) motors. These motors control gantry systems that support, convey, and weld parts.


I support three machines that are approximately 3, 2, and 1 years old. I'll name them FSW1, FSW2, and FSW3, repsectively. They use the same motion hardware and (custom) software.


FSW3 is frequently faulting for "motor #4 faults". Sometimes, I encounter five faults per hour. Other times, I encounter one fault per 4 hours. Even idle (i.e., the motor is servoing but is under no load), motor #4 will fault. When a motor #4 occurs, the following things happen:

  1. PEWin32Pro2 displays motor status 4, bit 3 "Amplifier Fault" is TRUE. I have not seen other error bits become TRUE.
  2. Motor 1 may or may not be operating eratically (short, jerky movements back and forth; makes alot of rumbling noise; motor counts change maybe +/-25). "Amplifier Fault" or other faults have not turned TRUE for motor 1.
  3. "Amp Status" LED on front GeoBrick panel may or may not display an intermittent blinking zero. It always displays a blinking dot. Typically, when a motor #4 fault occurs, and motor #1 is "rumbling", the "Amp Status" has a blinking zero.


When an error occurs, I initialize Turbo PMAC and rehome all axes. FSW typically resumes running without problem until the next "motor #4 fault".


The machine builder first asked that I verify electrical connections. That is done and everything appears ok. I have scheduled downtime to very leadscrew systems. I have moved all axes by hand, and everything is smooth and as expected.


Next, the machine builder had me restore the original PMAC configuration file. That is done, and it did not make a difference.


Next, the machine builder asked that I "dampen" the tuning a little bit. He advised me to reduce I435 (motor 4 PID acceleration feedforward gain) by 50%. I did, and it did not make a difference. As an aside, Delta Tau tech support did not believe adjusting this variable was appropriate.


Next, the machine builder advised me to retune motor #4. I have downloaded tuning documents from this forum, but the whole thing might as well be written in Greek because I understand little. I will ask for assistance from the machine builder.


Next, the machine builder advised me to replace the following in order: motor #4, motor #4 cables, GeoBrick. I am in the process of ordering a motor and motor cables. I do have a spare GeoBrick, and I am tempted to replace it and see what happens.


Tech support, after receiving the machine configuration file, asked that I verify Hall Sensor operation on motor #4. Per tech support's description, motor #4 hall sensors look ok.


One of the forum topics suggesting running a "HallsUVW.exe". I have done that, and it did not make a difference.


The tuning .pdf procedure recommends numerous I variables to investigate. If anyone can expound on/advocate certain variables and explain it to me like I'm a fourth-grader, I would greatly appreciate it.


[/u]Thanks again for your time and effort.

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Indeed I would also suspect that the tuning could be causing the amplifier faults. Sometimes, if the tuning is too severe or has some noise issues, a servo command that is too severe for the motor can be commanded. Something else to monitor in the Motor Status window at the time of a fault is whether your I2T Fault is high. In this case, the PMAC is killing the motors because you are exceeding the permissible integrated current limits.


It would most likely be easiest if I explained the tuning guidelines to you over the phone. Can you call me sometime next week (week of 1-27-13) after 830 am PST? The Technical Support Hotline is 818-717-5656, just ask for Charles.

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Hi Charles,


Thanks for the reply! I will indeed call per your instructions. I look forward to talking in person.


I have gotten into the habit of taking a "PEWin32Pro2 Motor 4 Status" screenshot in the event of a motor #4 fault. Of those that I have taken, all indicate a "Bit 3 - Amplifier Fault error". I haven't yet seen a "Bit 5 - I2T Amplifier fault error", but I will certainly pay close attention to that.


Thanks again.

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