On Monday 16 December 2019 18:40:35 John Dammeyer wrote: > > -----Original Message----- > > From: bari [mailto:bari00...@gmail.com] > > Sent: December-16-19 10:51 AM > > To: emc-users@lists.sourceforge.net > > Subject: Re: [Emc-users] Latency Warning Messages > > > > It depends on how you configure and run Linuxcnc with your intended > > hardware. > > > > In the .INI file there is a section EMCMOT > > http://linuxcnc.org/docs/2.6/html/config/ini_config.html#sub:EMCMOT- > > section > > > > The settings you place in BASE_PERIOD and SERVO_PERIOD set the > > length of each of these task periods for Linuxcnc. > > > > BASE_PERIOD = 50000 - the Base task period in nanoseconds. > > > > SERVO_PERIOD = 1000000 - This is the "Servo" task period in > > nanoseconds. > > > > If either thread run by the processor takes longer than the times in > > these settings you will see a latency message for it taking too > > long. This can be caused by things like trying to step too quickly > > (moving the motors faster) using the base period with a LPT port or > > by using too low a setting for the task periods to begin with based > > on your hardware and BIOS settings. > > > > How to choose your base period: > > http://wiki.linuxcnc.org/cgi-bin/wiki.pl?TweakingSoftwareStepGenerat > >ion > > > > The reason that you stopped having the latency messages when you > > changed > > from software stepping on the LPT port to hardware stepping on the > > MESA 7i92H is that you changed from using the Base Period (very > > short, fast) to the Servo Period (much slower) from the CPU's > > perspective. This allows you to use a PC with longer latency or > > higher jitter. > > > > On 12/16/19 12:03 PM, John Dammeyer wrote: > > > That's what I've found. When I run the test software to determine > > > > machine latency the on board video provides the smallest number. > > Any of the add on boards I tried all gave much worse numbers. > > For example. The board in the machine at the moment generates a Servo > Jitter of 33217 and Base Jitter of 131983. Thats pretty slow john, I'd take that machine to the office and bring out the office machine. It might just be faster. :)
> For the MESA and PP > configuration I have: > BASE_PERIOD = 24000 > SERVO_PERIOD = 1000000 > > If I understood the document link above correctly I should have set > the base to at least 132000 which would limit my step rate to about > 3kHz. The video board is a ow profile card that has a DVI connector > out and can run to two VGA monitors. Really just designed for desktop > PC's that need multiple monitors to display government forms or > whatever. The Lenovo PC and card came from the government surplus. > > Now if I remove the video card and run the latency test for the on > board video I get a Servo Jitter of 351232 and Base Jitter of 418333. > > Setting the .ini BASE_PERIOD to 420,000 results in no longer getting > the initial servo message. Of course now step rates are so severely > restricted that jog on the X axis results in an immediate following > error. > > I believe that the DC Servos are more forgiving if the step pulses are > occasionally held back since the internal step counter is compared > against the encoder counter and a following error fault by the motor > only happens if it reads more encoder counts than received on the step > input. Probably why with the video board installed and the initial > error that I don't get faults. > > And none of that is an issue with the MESA card. > John > > > > Also, if I understand how this works, if the fastest speed > > > required for > > > > stepping is not to high then you won't get the messages. But if > > your step rates are up into 50kHz and higher then you get that > > warning once when you start up LinuxCNC. > > > > > But I may have it all wrong. For my current testing I get that > > > message > > > > when I use the parallel port but it doesn't appear to affect the > > step rates to the drives. I just dispose of the message. But > > that's because I don't care at the moment. I'll switch to the MESA > > once the testing and development is done. > > > > > John > > > > > >> -----Original Message----- > > >> From: N [mailto:nicklas.karlsso...@gmail.com] > > >> Sent: December-16-19 9:38 AM > > >> To: Enhanced Machine Controller (EMC) > > >> Subject: Re: [Emc-users] Latency Warning Messages > > >> > > >>> I bought 3 different low profile video cards to try and get rid > > >>> of that > > > > latency > > > > >> message. The ultimate and best solution was to buy the MESA > > >> 7i92H. > > > > Does > > > > >> away with the parallel port completely. > > >> > > >>> John Dammeyer > > >> > > >> The parrallel port cause latency messages? > > >> > > >> > > >> _______________________________________________ > > >> Emc-users mailing list > > >> Emc-users@lists.sourceforge.net > > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
