I’m currently working with a Velocity 11 Vspin (now Agilent). To make it easier to operate, I built a custom GUI. I’m using parts of pylabrobot, but had to write some custom fixes myself since the centrifuge is quite old.
The centrifuge itself works fine, but I’m running into a specific issue with the loader.
The Problem: Right after the homing sequence, the loader throws the following firmware error:
Firmware error: Position error on Z command id = 40, command number = 11
Error: Firmware error: Position error on Z
Visually, the homing process looks completely normal and seems to finish successfully, but this error pops up right at the very end.
What I’ve checked so far:
I’ve inspected the relevant sensors: the encoder [4], the Hall sensor [3], and the inductive sensor[1] (which is shared with the Y-axis).
I have already reset the parameters back to factory defaults, but the issue persists.
My Questions:
Am I missing another limit switch somewhere on the Z-axis that might be defective?
Has anyone experienced this specific Z-axis position error with the V11 loader before, and does anyone have an idea what else could be causing it?
I’ve attached some pictures of my GUI and the centrifuge setup below for better context.
I don’t have the Agilent software for it. However, I get the same error in the Diagnostics Software as I do with the Python code. The error just isn’t very specific; if you unplug for example the Hall sensor on the Z-axis, it throws the same error right away.
@TheLucas Does the Z axis move during initialization? The unit only has the 1 limit sensor for the z axis. If the z axis does not move, it could be the motor.
Visually, both the Y and Z axes are actuating normally. The loader physically completes the homing sequence, but throws the position error at the moment you’d get the ‘homed’ status.
@TheLucas Does the Z axis sensor trip when the Z goes down? I have seen issues with the sensor failing. It could also be the Access2 main board. It’s hard to troubleshoot without seeing it in person.
Thanks for your inputs - you’re right.
The LED of the senor is turning on/off but on the status panel on the backside of the device, the sensor is not causing any changes.
The sensors for the Y-axis and plate presence are toggling correctly (on/off). However, there is no state change for the Z-axis. I suspect the Z-axis sensor corresponds to one of the LEDs i marked violet.
It turns out the Z-axis sensor is actually dead. I measured the output signal and got absolutely nothing. The status LED on the fork sensor correctly toggles on and off when an object interrupts the beam, which falsely implies the sensor is fully functional.
Codex integrated it into the library, i will do a review and testing on the hardware on monday.
Since there were a few differences, i guess there must be differnt versions over the past 20 years.
I have a similar problem with our Agilent VSpin. We bought the unit refurbished few months ago and it worked fine for 1-2 months but yesterday the arm stopped homing during initialization. The specific error is:
Firmware error: Position error on Y
In the VWorks, the z axis servo initializes successfully:
The marked LEDs are constantly off and comparing this to @TheLucas board they should be on. Did anyone run into a similar problem? Would this be a motor issue and are there additional steps I can take to confirm?
Unfortunately i couldn’t reproduce your error. (I also tried initialization with unplugged sensors)
But to mention: Our Centrifuge is a Velocity 11, not Agilent. They made some changes in the past 20 years.
Hi @dcmay I inherited this issue from @rkaptur. The Y axis or any other axis does not move (home) before the error. I opened it up and there is no discernible movement of the motor for the y-axis when sending the initialize command (via Vworks.) The mounting also seems to be intact
