Re: [CAD_CAM_EDM_DRO] determining stepper motor current

alan,
The ref volts is the chopper cutoff current setting reference.
VRef divided by sense res ohms = current setting.
or
Max current times sense res = VRef

The motor rating is the max setting for VRef calc.
Set it to the max allowed for the motor.
OTOH, what voltage is your power supply? The L298 allows ~30 max.
This is where the Omph! comes from.
RichD

alanhunt2001 wrote:

>
> I have a Step 4 cnc machine for which I've built a new controller
> based on L297/298 combo (as the original went up in smoke) I'm
> having trouble determining the vref setting. The motors are marked
> nanotek - munich 1.8deg/step 1.2ohm. '17' size and I think they were
> originally set up for a max current of 0.8A. I am trying them at the
> moment with vref=0.4v and with sense resistors of 0.5ohm , but the
> motors do not have any of their original torque.
>
> As I understand, I am effectivly setting the current as the peak
> current which will be much less then the average current. I am wary
> of increasing the current without any more data on the motors.
>
> any suggestions will be appreciated.
>
> alan