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?TweakingSoftwareStepGeneration 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. > > 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
