Hi all,
We have been working late here trying to deal with what I think is a bug with PCI-NI7358, NI-motion / Flexmotion 7.4 & 6.1.2.
Basically when a gear ratio of 1:1 is applied and the master is set spinning normally the motor shafts maintain the same relative angle because the motors are being sent the same pulses. But this is only true at certain speeds it seems. Our system goes wrong at 80rpm and 100rpm and somewhere around 400rpm and I expect many other speeds. I think this is a bug because when the motors are set spinning at these speeds independently without the electronic gear enabled the motors behave as expected. As soon as electronic gearing is used the relative angle of the motor shafts drift apart, one motor must be going slower than the other. This happens when the master is in open or closed loop mode.
We found a crazy work around for this (might work for our application): using NI-motion 6.1.2 (LabVIEW 6i era!) firmware for FPGA & DSP on the card, with the master in closed loop mode, while the master is in velocity mode and spinning, keep telling the master to start (using multi-start) and then the motors appear to spin at the same speed. Who knows why? I expect the error is still occurring but gets corrected every time we execute multi-start. Some nasty floating point error on the card I expect.
Anyway please correct me if I'm wrong here (hope I am!). We urgently need a solution to this as even the workaround is not usable at the moment because we can't figure out how to do what we need when the master is in closed loop mode (see my other post: closed loop stepper and gearing issue). And yes, I know we should be using the latest version of the firmware etc but the issue in my other post still exists when using the latest versions.
Kind regards / Martin
