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From: Andrew <par...@gm...> - 2011-07-03 13:24:45
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2011/7/3 andy pugh <bod...@gm...>: > On 3 July 2011 13:34, Andrew <par...@gm...> wrote: > >> I'd prefer not to mess with homemade conversion, but 2 x 7i33TA = >> $160, not so cheap. > > I missed the bit where you said you were connecting 6 motors. Visteurs > has pointed out a more suitable card. I also need to control spindle VFD, but I'd prefer Modbus over analog. Can I use 7i43 for Modbus? >> By the way, DMM Tech has optional SPI control for servo drives. I >> wouldn't need that nasty pwm-to-analog conversion, if purchased those >> drivers =( > > Maybe not, but you might end up putting the PID loop in the drive > rather than in EMC2, and that's not the preferred way. Yes, there's internal PID loop in step/dir mode already, but I do not like the way it works. When you put some torque (not so large) to the shaft, it rotates significantly, then goes back. Also overshoot is pretty large, etc. > (I would need to check the DMM docs to see if the SPI commands are > position or velocity or torque) My drivers have no SPI, unfortunately. But position/velocity/torque mode is switched through driver software, I guess the same is for SPI. Andrew |