[Emc-users] Mesa 7i77 encoder max count rate

[Marius A. <mar...@gm...>]

In my current linuxcnc, 5i25 and 7i77 setup I get 1MHz maximum encoder 
count rate. Is it possible to increase it?

I want to run a spindle up to 10k RPM with resolver. There is a resolver 
to quadrature converter, giving 16384 counts per revolution. That's 
5.461 MHz.

Encoder velocity output goes crazy above 4000 RPM roughly. That's about 
1 M counts / s.

It might be not possible for Mesa 7i77 while using 4 channels. I will 
try to reduce output scale of the converter, but would like to get more 
from 7i77. Can't find how.

Another approach would be to look at the index pulse width and if it is 
wide enough, count it with another encoder channel in count mode and 
make custom HAL component to switch between feedback devices. I need 
accuracy for slow moves and spindle orientation and velocity at higher 
speeds.

Using probably the latest firmware for Mesa cards and updated LinuxCNC 2.7.