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The Software

Last update: 31/07/2015

A new RTAI distribution, faster and updated, of Ubuntu RTAI has been created recently to be used in connection to a cnc machine and EMC2 (rel. 2.4.3) the CNC software. The setup of EMC2 included in this release is easier and more complete compared to the previous releases. But unexperienced linux user can still find some difficulties on various, simple, aspects.


We have to say that at the moment we have installed this new release on a couple AMD Athlon X2 machines and double core Intel machines (both with 2GB of ram, nvidia video, sata hds) without problems but we have not been able to install it on motherboards using Atom processors, very probably due to kernel limits.

There are two different ways to setup a pc with Linux RTAI version: 

  • installing an Ubuntu 10.04 normally and execute the script descripted on the page;
  • download a live already precompiled ISO and install it on the pc.

In any case the procedures are the usual procedures necessary to install any Ubuntu Linux distro. The setup of the live image (links) is, in fact, traditional and almost nothing is changed from previous versions of the operative system (8.04, 6.06). Naturally also this version can be used as live cd at firts, to be installed permanently after the tests. EMC2 requires very few and simple settings to the standard setup of the operative system to avoid malfunctions (and a further reinstall of the software of the machine) and setup the machine accordingly to our need.

linux update 

Disable the software update.

The kernel and some libraries cannot be updated.
Therefore it is necessary to disable permanently the update service.

It can be done very quickly just click on:

system - preferences - startup application (and disable the update notifier at boot.

 linux update


system - administration - update manager

click on settings and

 linux update

Clear all marks. The job is done.

 emc2 config

Choose a name for your cnc machine configuration, choose the units. The driver timing settings are normally reported on any commercial driver/controller for stepping motors.

It represents (for any step) the time necessary for the step to stay in the ON state and the time necessary for one step to another. The same for directions. Please consider that these values are wide enough for almost all controllers on the market.

Leave them unchanged for the moment or write the values reported by the driver usTest the base period jitter and report the value suggested. The max step rate is automatically calculated.

Check and test again these value if, during the use, the machine suffer from step loss.

 emc2 config

Set the parameters according to your controller and cnc machine. For this cnc machine only one step is used to enable all controllers.

Really interesting is the use of all pins connected to the sensors.  Hundred of different combinations are possible according to our needs and to the cnc machine used.  


 emc2 config

Very easy is the setup of the three axes configurations.
The program calculates automatically, if present, the pulley ratio just writing the number of teeth and microstepping value. regarding the speed and the acceleration the right value can be found just testing the axis.

This setup must be done for any axis present in the machine (usually three ofcourse)

 emc2 config

Al temine della procedura di setting viene creato sul desktop un file di lancio ed una directory contenente tutti i parametri per la nostra macchina. Cliccando sul launcher si avra' un errore che e' possibile correggere immediatamente:

clikkare sull'icona con il tasto destro, quindi property e selezionare 'allow executing file as program'.

Il lavoro e' terminato ed il software e' pronto.

 emc2 config

It works!!

 emc2 config The directory created, MYCONFIG, contains all the files created during the setup (MYCONFIG.hal, MYCONFIG.ini). These files, particularly by experienced users, can be changed directly by an editor to modify all the settings of EMC2 without starting the wizard again (if needed).

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