On Wed, 14 Oct 2009, Chris Morley wrote: > Date: Wed, 14 Oct 2009 01:39:16 +0000 > From: Chris Morley <[email protected]> > Reply-To: EMC developers <[email protected]> > To: EMC DEV <[email protected]> > Subject: Re: [Emc-developers] hostmot2 stepping folowing error oddity > > > > >> Date: Tue, 13 Oct 2009 08:06:00 -0700 >> From: [email protected] >> To: [email protected] >> Subject: Re: [Emc-developers] hostmot2 stepping folowing error oddity >> >> On Tue, 13 Oct 2009, Sebastian Kuzminsky wrote: >> >>> Date: Tue, 13 Oct 2009 08:57:34 -0600 >>> From: Sebastian Kuzminsky <[email protected]> >>> Reply-To: EMC developers <[email protected]> >>> To: EMC developers <[email protected]> >>> Subject: Re: [Emc-developers] hostmot2 stepping folowing error oddity >>> >>> Peter C. Wallace wrote: >>>> On Mon, 12 Oct 2009, Chris Morley wrote: >>>>> I'm having a little problem with a hostmot2 stepper setup. >>>>> I get following errors that I can't track down a reason for. >>>> >>>> Is it possible you simple dont have enough hardware headroom to reach you >>>> max >>>> velocity? With 200 usec StepLen and 200 uSec StepSpace, the maximum step >>>> rate >>>> the hardware can generate is = ~2500 Hz, I just glanced at the ini file but >>>> doesn't a Scale of 2800 mean 2800 steps per inch? If so the maximum >>>> velocity >>>> should be about 10% less than 2500/2800 (10% for headroom). about .8 inches >>>> per second. >>> >>> I agree it's a "max physical step rate" vs "trajectory-planner max >>> commanded velocity" problem, but i think there is no headroom problem. >> >> Well semantics... to me its a _hardware_ headroom problem, the hardware >> stepgenerator is being asked to step faster than its capable of stepping. >> >> Chris: can you try setting max_velocity to .8 so theres no chance the >> trajectory planner can outrun the stepgenerator? I think all bets are off >> without this. >> > > I will try this later hopefully tonight. > Interestingly the reason I was using 100 inches per minute (1.667 ips)... > Pncconf has a 'tune test' that sets the hostmot2 stepgen's > max velocity and max acceleration. It would let me move at > aprox 150 inches per minute. It does not keep track of following error > though. So I detuned it to 100 ipm and ran EMC. I'm not sure how > hostmot2's stepgens decide on whether it can or cannot move at a > specific drive timings and max speed etc.
At the lowest (hardware) level, the stepgen will not run faster than 1/(StepLen+StepSpace) regardless of whats programmed in the velocity register. one level above that the HostMot2 driver will not use a velocity greater than xxxx.maxvel. If .xxxx.maxvel is set to 0 the driver will chose maxvel based on the StepLen and StepSpace settings (with some headroom I hope). > But all that aside I still don't see why moving negative and positive > is so dramatically different - but then again I know nothing about > stepgenning and trajectory planning :) I dont know why they should be so different either, It would be interesting to see what the velocity limits were in either direction of motion. I dont see why they wouldn't be symmetrical. > > Chris M > _________________________________________________________________ New: Messenger sign-in on the MSN homepage http://go.microsoft.com/?linkid=9677403 Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
