Getting Started Guide V2.5

The minimum system to run EMC2 and Ubuntu may vary depending on the exact usage. Stepper systems in general require faster threads to generate step pulses than servo systems. Using the Live-CD you can test the software before committing a computer. Keep in mind that the Latency Test numbers are more important than the processor speed for software step generation. More information on the Latency Test is in Section ( [sub:Latency-Test]).

Additional information is on the EMC Wiki site:

http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Hardware_Requirements

EMC2 and Ubuntu should run reasonably well on a computer with the following minimum hardware specification. These numbers are not the absolute minimum but will give reasonable performance for most stepper systems.

Ubuntu has been chosen, because it fits perfectly into the Open Source views of EMC2:

IRC stands for Internet Relay Chat. It is a live connection to other EMC users. The EMC IRC channel is #emc on freenode.

The simplest way to get on the IRC is to use the embedded java client on this page http://www.linuxcnc.org/content/view/4/8/lang,en/.

Some IRC etiquette:

http://pastebin.ca = for text  +
http://imagebin.ca = for pictures +
http://filebin.ca = for files and pdfs

An Internet Mailing List is a way to put questions out for everyone on that list to see and answer at their convenience. You get better exposure to your questions on a mailing list than on the IRC but answers take longer. In a nutshell you e-mail a message to the list and either get daily digests or individual replies back depending on how you set up your account.

Information about the EMC Users Mailing List at:

https://lists.sourceforge.net/lists/listinfo/emc-users

A Wiki site is a user maintained web site that anyone can add to or edit.

The user maintained EMC Wiki site contains a wealth of information and tips at:

http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl

Download the Live CD from:

http://www.linuxcnc.org/

and follow the Download link.

If the file is too large to download in one session because of a bad or slow Internet connection use wget to allow resuming downloads.

EMC2 is distributed as CD image files, called ISOs. To install EMC2, you first need to burn the ISO file onto a CD. You need a working CD/DVD burner and an 80 minute (700 Mb) CD for this. If the CD writing fails, try writing at a slower burn speed.

With the Live CD in the CD/DVD drive shut down the computer then turn the computer back on. This will boot the computer from the Live CD. Once the computer has booted up you can try out EMC2 without installing it. You can not create custom configurations or modify most system settings like screen resolution unless you install EMC2.

To try out EMC2 from the Applications/CNC menu pick EMC2. Then select a sim configuration to try out.

To see if your computer is suitable for software step pulse generation run the Latency Test as outlined in Section ( [sub:Latency-Test])

If you like what you see, just click the Install icon on the desktop, answer a few questions (your name, timezone, password) and the install completes in a few minutes. Make sure you write down the name you used and the password. Once the install process is complete and you go on line the update manager will pop up and allow you to upgrade to the latest stable version of EMC2.

The AXIS interface is one of the interfaces to choose from. It can be configured to add a Virtual Control Panel to customize the interface to suit your needs. AXIS is the default user interface and is actively being developed.

With the normal install the Update Manager will notify you of updates to EMC2 when you go on line and allow you to easily upgrade with no Linux knowledge needed. If you want to upgrade to 10.04 from 8.04 a clean install from the Live-CD is needed. It is OK to upgrade EMC when asked to.

Warning: Do not upgrade Ubuntu to a new version (like 8.04 to 8.10) as it will prevent EMC from running.

In rare cases you might have to reset the BIOS to default settings if during the Live CD install it can not recognize the hard drive during the boot up.

The Latency Test determines how late your computer processor is in responding to a request. Some hardware can interrupt the processing which could cause missed steps when running a CNC machine. This is the first thing you need to do. Follow the instructions in section ( [sub:Latency-Test]) to run the latency test.

If you have a Sherline several predefined configurations are provided. This is on the main menu CNC/EMC then pick the Sherline configuration that matches yours and save a copy.

If you have a Xylotex you can skip the following sections and go straight to the Stepper Config Wizard in Section ( [cha:Stepconf-Wizard]). EMC has provided quick setup for the Xylotex machines.

Gather the information about each axis of your machine.

Drive timing is in nano seconds. If you’re unsure about the timing many popular drives are included in the stepper configuration wizard. Note some newer Gecko drives have different timing than the original one. A list is also on the user maintained EMC wiki site of more drives at http://wiki.linuxcnc.org.

Gather the information about the connections from your machine to the PC parallel port.

Note any pins not used should be set to Unused in the drop down box. These can always be changed later by running Stepconf again.

Gather information on steps and gearing. The result of this is steps per user unit which is used for SCALE in the .ini file.

Steps per revolution is how many steps it takes to turn the stepper one revolution.

Micro steps is how many steps the drive needs to move the stepper one step.

Motor & Leadscrew Teeth is if you have some reduction between the motor and the leadscrew. If not set these to 1.

Leadscrew pitch is how many turns it takes to move your table one user unit. If you’re setting up in inches then it is turns per inch. If you’re setting up in millimeters then how many millimeters per turn.

Run the Stepconf Wizard in chapter ( [cha:Stepconf-Wizard])

To change something in the basic configuration created by Stepconf Wizard run the wizard again. Select Modify a configuration… Then pick the configuration file .stepconf you wish to modify in the emc2/configs folder. The file headers tell you if the file can be manually edited or not.

.

Figure 7.4. Parallel Port Setup Page

For each pin, choose the signal which matches your parallel port pin out. Turn on the "invert" check box if the signal is inverted (0V for true/active, 5V for false/inactive).

Figure 7.7. Spindle Configuration Page

This page only appear when "Spindle PWM" is chosen in the Parallel Port Pinout page for one of the outputs.

Click “Apply” to write the configuration files. Later, you can re-run this program and tweak the settings you entered before.

For each axis, there is a limited range of travel. The physical end of travel is called the hard stop.

Before the hard stop there is a limit switch . If the limit switch is encountered during normal operation, EMC shuts down the motor amplifier. The distance between the hard stop and limit switch must be long enough to allow an unpowered motor to coast to a stop.

Before the limit switch there is a soft limit . This is a limit enforced in software after homing. If a MDI command, or g code program would pass the soft limit, it is not executed. If a jog would pass the soft limit, it is terminated at the soft limit.

The home switch can be placed anywhere within the travel (between hard stops). As long as external hardware does not deactivate the motor amplifiers with the limit switch is reached, one of the limit switches can be used as a home switch.

The zero position is the location on the axis that is 0 in the machine coordinate system. Usually the zero position will be within the soft limits. On lathes, constant surface speed mode requires that machine X=0 correspond to the center of spindle rotation when no tool offset is in effect.

The home position is the location within travel that the axis will be moved to at the end of the homing sequence. This value must be within the soft limits. In particular, the home position should never be exactly equal to a soft limit.

The ideal wiring for external switches would be one input per switch. However, the PC parallel port only offers a total of 5 inputs, while there are as many as 9 switches on a 3-axis machine. Instead, multiple switches are wired together in various ways so that a smaller number of inputs are required.

The figures below show the general idea of wiring multiple switches to a single input pin. In each case, when one switch is actuated, the value seen on INPUT goes from logic HIGH to LOW. However, EMC expects a TRUE value when a switch is closed, so the corresponding "Invert" box must be checked on the pinout configuration page.

Wiring N/C switches in series (simplified diagram)

Wiring N/O switches in parallel (simplified diagram)

The following combinations of switches are permitted in Stepconf:

The last two combinations are also appropriate when a "home to limit" is used.

Here you can select from different GUI’s and options for each one.

Figure 8.3. GUI Configuration

On this page you can add additional HAL components you might need.

Figure 8.11. HAL Components

When you install EMC2 with the Ubuntu LiveCD the default is to have to log in each time you turn the computer on. To enable automatic login go to System/Administration/Login Window. If it is a fresh install the Login Window might take a second or three to pop up. You will have to have your password that you used for the install to gain access to the Login Window Preferences window. In the Security tab check off Enable Automatic Login and pick a user name from the list (that would be you).

To have EMC start automatically with your config after turning on the computer go to System/Preferences/Sessions Startup Programs , add new. Navigate to your config and select the .ini file. When the file picker dialog closes add emc and a space in front of the path to your .ini file.

Example:

emc /home/mill/emc2/config/mill/mill.ini

Man pages are automatically generated manual pages in most cases. Man pages are usually available for most programs and commands in Linux.

To view a man page open up a terminal window by going to Applications, Accessories, Terminal. For example if you wanted to find out something about the find command in the terminal window type:

man find

Use the Page Up and Page Down keys to view the man page and the Q key to quit viewing.

Sometimes when troubleshooting you need to get a list of modules that are loaded. In a terminal window type:

lsmod

If you want to send the output from lsmod to a text file in a terminal window type:

lsmod > mymod.txt

The resulting text file will be located in the home directory if you did not change directories when you opened up the terminal window and it will be named mymod.txt or what ever you named it.

When you open the file browser and you see the Owner of the file is root you must do extra steps to edit that file. Editing some root files can have bad results. Be careful when editing root files. You can open and view most root files normally but they will open in “read only” mode.

sudo gedit

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