Re: [Emc-users] MESA 7i43

[Andrew <par...@gm...>]

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