# Driving minimum speed with the L6480

Question asked by seckinger.stefan on May 13, 2014
Hi everyone,

I'm driving 3 stepper motors in a daisy chain configuration. In order to start and stop all 3 motors the same time, I'm calculating the speed and acceleration values for each motor and write down the configuration. So far everything works fine!

When I'm now trying to drive a long way with the first motor and a very short way with another motor the stopp time is not the same any more. The short path ends first. So there is a problem with the minimum speed I can reach...

In the datasheet there's a note, that the minimum speed is 15,25 [steps/s] with the GoTo-command.

I'm using 32 microsteps and the motors have a step angel of 1.8°. So the amount of microsteps per turn is 1.8[°]/32[microsteps] = 0,05625 [°/microstep] and 360[°]/0,05625[°/microstep] = 6400 [microsteps per turn].

Having a rising spindel with 2[mm], I get an amount of way per microstep of 2/6400 = 0,0003125[mm/microstep]. So with a minimum speed of 15,25 [steps/s], the minimum driving speed I can reach is 15,25*0,0003125 = 0,004765625[mm/s].

Am I calculating this the right way?

The minimum turning speed I reach is much higher than 0,0047[mm/s]. I have read out the registers and there's a 0 in the max speed and acceleration registers. So I think there must be a calculating error.

Using the Run-Command I can drive with very low speed. So I guess it must be possible with the GoTo-Command, too.

Thanks in advance for every hint and post.

Kind regards,
Stefan