7i80hd + 7i39?

Hello,

i was wondering if the 7i80hd and 7i39 are compatible, because i need one more axis (using the 7i39 as a spindle drive). Also when i would want the spindle to have a maximum rpm of 15.000, is the maximum encoder count rate (1mhz) enough when i use a 512ppr encoder? if i calculated correctly the encoder only generates up to 128khz (or 512khz with quadrature).

if not compatible, is there any other board i could use as an extra axis? something like the stmbl drive but unfortunately this is not available

thanks

The 7I39 and 7I80HD are compatible hardware wise, but I don't think the 7I39 would be a good match for a high speed spindle due to the fact the the commutation needs to be done in software by LinuxCNC in the servo thread. This is OK for lower speeds but not going to work well at high RPMs