Max pulse rate question

[Tim Berframe]

Im trying to use CW250 open loop stepper drivers. They have a maximum pulse rate of 75khz, 1600 pulses/rev.

The smallest option in the setup is 100khz.


Given the gear reduction and max travel speeds I would safely want to use ( 1 motor rev = .785" linear travel or 1.2739 revs = 1" linear travel), the drivers should never exceed 34000 pulses/second.

Should these work with the max setting at 100k ? or is pulse width affected here somehow that is causing problems?

While bench testing, my test motor ( xaxis) locks but will not turn.

[eng199]

Set parameter 968 to 16.
The width of the step pulse is constant at a given p968 setting, so the step rate has to be set low enough for the drive. Otherwise, the short step pulse may be missed by the drive.

[cnckeith]

if you really need lower than 100k then you need new modern drivers. spring for the $20 and get new drives.

[Tim Berframe]

Thanks for the suggestions. I changed parameter 968 to value 16 (75khz) and it didn't help.

I was hoping to get it running so I could test table flatness, bearings, spindle etc before deciding on motor upgrades. I guess Ill have to gamble on all that some more and just get the Clearpaths or closed loop package now. "Cheap" drivers in Canada are more like $75 each and that is half way to StepperOnline closed loop package price.

The only other thing I was wondering about is the axis signal inversion.

The db25 connections are joined to the negative poles on the drivers so Acorn is sinking the supplied 5v to common (S14976). Should the drives signal inversion boxes be checked on? The drives have no enable terminal. Should the enable box be checked on?

[ShawnM]

Do yourself a HUGE favor and don't even waste your money on more open loop stepper drives. Buy decent closed loop steppers or better yet the Clearpath servos as you mentioned. Far superior to ANY stepper setup. It's best to build the system right the first time instead of wasting more money later wishing you would have just upgraded the machine right in the beginning. You wont be disappointed.

[cnckeith]

The only other thing I was wondering about is the axis signal inversion.

The db25 connections are joined to the negative poles on the drivers so Acorn is sinking the supplied 5v to common (S14976). Should the drives signal inversion boxes be checked on? The drives have no enable terminal. Should the enable box be checked on?

only way to find out is to try it. btw hook up and run one axis at a time is a good debug strategy.