I have been following this thread with great interest. I presume the 7i49 (six-input resolver) is similarly affected due to its use of SPI to the mothercard? Is this so? I have a 7i49 here if it will help in any way (indirectly) with the 7i65.
Also, note that doubling the speed of the servo thread may not always be available as a solution. I'm working on a unit now with a "medium" ladder (admittedly on an older PC) where I felt I should halve the servo thread to keep ClassicLadder happy, at least for the moment. The jury is still out, and we're upgrading the PC, at least somewhat. Thanks very much, I look forward to hearing more on this. Kim On 04/28/2011 05:52 PM, Peter C. Wallace wrote: > On Thu, 28 Apr 2011, andy pugh wrote: > >> Date: Thu, 28 Apr 2011 23:29:26 +0100 >> From: andy pugh <[email protected]> >> Reply-To: EMC developers <[email protected]> >> To: EMC developers <[email protected]> >> Subject: Re: [Emc-developers] [PATCH] Add support for Hostmot2 Buffered SPI >> and the Mesa 7i65 >> >> On 28 April 2011 23:24, Peter C. Wallace <[email protected]> wrote: >> >>> Yes, you must send to receive with SPI so unless you want to duplicate the >>> sending (Looking at the 7I43 timing I would think not) you need to reverse >>> the >>> normal order of read write (for SPI only). This means that the read data is >>> always from the last thread invocations write, that is the read data is one >>> thread time late. This is fine for the 7I65 as the SPI input data is not >>> motion related. >> >> Ah, yes, I had forgotten that. >> Though I guess if somebody tried to use the analogue inputs to read >> tacho data to close a velocity loop they might have problems. > > Well say you have a 1 KHz servo thread rate. One way of looking at this is > that on the average, looking at high speed events, you are .5 mS late, If > your > data is always an additional 1 mS late you are now an average of 1.5 mS late. > So bumping up the servo thread rate to 3 KHz gets you back where you started. > (.5 ms average lateness = .333 mS for one servo period + 166 usec average > sampling delay) > > (3KHz and 7I65 not suggested for 7I43 however) >> >> ------------------------------------------------------------------------------ WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
