Linuxcnc 3d printer setup

Servo Period sets the system delay. Latency refers to the amount of time a computer can run longer than this period. LinuxCNC requires everything to be done within a very tight and consistent time frame, otherwise crashes will happen. LinuxCNC requires and uses operating system real-time , which simply means that it has a low latency response time when LinuxCNC requires its computations, and when LinuxCNC performs computations, it cannot be interrupted by lower priority requests (such as user input on on-screen buttons or drawing, etc. d.).

Latency checking is very important and should be checked early. Fortunately, by using the Mesa card for work that requires maximum response time (encoder counting and PWM generation), we can handle much higher latency than if we used the parallel port for these things. Standard test in LinuxCNC ( test base period jitter ) is a BASE period delay test (even if we don't use a base period). If you click the test base period jitter button, it launches the delay test window (you can also load it directly from the app/cnc panel). The test mentions to run it for a few minutes, but the longer the better. consider that 15 minutes is a minimum, and even better - a night. At this time, use the computer to boot, use the network, use USB, etc., we want to know the worst case latency and find out if any particular action affects our latency. We need to look at test base period jitter . Anything below 20000 is great - you can even do software quick stepping on a 20000 machine - 50000 is still good for software stepping and fine for us. 50000-100000 isn't really that great, but can still be used with fast response hardware cards. So we can use anything less than 100000.

Now we are happy with the delay and need to select a servo period. In most cases, a servo period of 1000000 ns is fine (which gives a servo calculation rate of 1 kHz - 1000 calculations per second) if you are making a closed loop servo system that controls torque (current) rather than speed (voltage) at a faster rate. It is better to have about 200,000 (calculated frequency 5 kHz). The problem with lowering the speed of a servo is that it leaves less time for the computer to do other things besides LinuxCNC calculations. Usually the display (GUI) becomes less responsive. You must decide on a balance. Keep in mind that if you tune a closed loop servo and then change the period of the servo, you will probably have to tune them again.

PNCconf can configure machines with two Mesa boards and three parallel ports. Parallel ports can only be used for simple low speed (servo speed) I/O.

You must select at least one Mesa board because PNCconf will not configure the parallel ports for encoder count, output step, or PWM signals. The mesa maps available in the selection box are based on what PNCconf finds for firmware on systems. There are options to add custom firmware and/or blacklist (ignore) some firmwares or boards using a settings file. If the firmware is not found, PNCconf will show a warning and will use the internal sample firmware - no testing will be possible. It should be noted that if you choose two PCI Mesa cards, it is currently impossible to predict which card is 0 and which is 1 - you should check - moving the cards can change their order. If you are configuring with two cards, both cards must be installed for the tests to work.

Up to 3 parallel ports can be used as simple I/O ports. You must specify the parallel port address. You can enter the Linux parallel port numbering system (0,1 or 2) or enter the actual address. The address for the built-in port is often 0x0278 or 0x0378 (written in hex), but can be found on the BIOS page. The BIOS page is located when you first start your computer. To enter it, you must press a key (for example, F2). On the BIOS page, you can find the parallel port address and set the mode such as SPP, EPP, etc. On some computers, this information is displayed for a few seconds during startup. For PCI parallel port cards, the address can be found by pressing button parport address . A help output page will open with a list of all PCI devices that can be found. It should contain a link to the parallel port device with a list of addresses. One of these addresses should work. Not all PCI parallel ports work properly. Either type can be selected as in (maximum input pins) or out (maximum output pins).

GUI Front-end list defines the graphical screens that LinuxCNC will use. Everyone has their own version.

AXIS

• fully supports lathes.
• the most developed and used interface
• is designed for use with mouse and keyboard
• is based on tkinter, so integrates PYVCP (Python-based Virtual Control Panels) naturally.
• has a 3D graphics window.
• allows integration of the VCP on the side or in the center tab

TOUCHY

• Touchy was designed to be used with a touch screen, some minimal physical switches and an MPG wheel.
• requires cycle start, interrupt and step signals and buttons
• also requires MPG common axis jog selection.
• is based on GTK so it naturally integrates GLADE VCPs (Virtual Control Panels).
• allows VCP panels to be integrated into the center tab
• does not have a graphic window
• the appearance can be changed with custom themes

MINI

• standard on Sherline OEM machines
• no integration with Estop
• does not use Estop 90 V14
90

TkLinuxCNC

• hello contrast bright blue screen
• separate graphics window
• no VCP integration

4. External configuration

This page allows you to select external controls, for example for rapid traverse or cancel.

PNCconf external configuration

If you select a joystick to move, it will always be connected to LinuxCNC for booting. In order to use the analog sticks for useful movement, you will probably need to add your own HAL code. MPG jog requires a pulse generator connected to the MESA encoder counter. Either a pulse generator (MPG) or switches (such as a rotary switch) can be used to control the interlock. The external buttons can be used with the stock switch-based joystick.

Joystick jogging

Requires custom device rule to be installed on the system. This is the file that LinuxCNC uses to connect to a list of LINUX devices. PNCconf will help make this file.

Search for device rule ( Search for device rule ) will search the system for rules, you can use this to find device names you already created with PNCconf.

Add a device rule ( Add a device rule ) will allow you to configure a new device by following the prompts. You will need your device.

Test device ( test device ) allows you to boot a device, see its contact names and test its functions with a HALmeter.

Joystick uses HALUI and hal_input components.

External buttons

Allows you to move the axis with simple buttons at a given speed. Probably best for fast travel.

MPG Jogging

Allows the use of a manual pulse generator to move the machine axis.

MPG is often found on commercial grade cars. They provide quadrature pulses that can be counted using the MESA encoder counter. PNCconf allows you to use an MPG for each axis, or one MPG common to all axes. This allows you to select jog speed with switches or single speed.

The selectable increment option uses the mux16 component. This component has options such as Reaction and Gray Code to help filter out the raw switch input.

Overrides

PNCconf allows you to change the feedrate and/or spindle speed using a pulse generator (MPG) or switches (eg rotary).

5. GUI configuration.

Here you can set default values ​​for display screens, add virtual control panels (VCPs), and set some LinuxCNC options.

PNCconf GUI Configuration
Front-end GUI Options

Default Options allows you to select general default options for any screen.

AXIS default values ​​are AXIS specific settings. If you choose size, position, or forced deployment options, PNCconf asks if the settings file (.axisrc) can be overwritten. If you didn't manually add commands to this file, that's fine. Position and maximum force can be used to move AXIS to a second monitor if the system supports this feature.

Touchy default settings are Touchy specific settings. Most Touchy settings can be changed while Touchy is running using the settings page. Touchy uses GTK for screen rendering, and GTK supports themes. Themes control the main appearance of the program. You can download themes from the internet or edit them yourself. The computer has a list of current themes that you can choose from. To highlight a portion of text, PNCconf allows you to override the default theme values. The position and maximum force options can be used to move the Touchy to a second monitor if the system supports it.

VCP Options

Virtual Control Panels let you add customizable controls and displays to your screen. AXIS and Touchy can integrate these controls within the screen at specific locations. There are two types of VCP: pyVCP which uses Tkinter to render the screen, and GLADE VCP which uses GTK .

PyVCP

The PyVCP screen XML file can only be created manually. PyVCP fits naturally into AXIS as both use TKinter.

HAL contacts are created for connecting a user inside their user HAL file. There is a sample spindle display panel that the user can use as is or add on. You can select an empty file, which you can then add controls to widgets or select a sample spindle display that will display the spindle RPM and also indicate if the spindle is at the desired speed.

PNCconf will wire the appropriate spindle display HAL pins for you. If you are using AXIS, the panel will be integrated on the right side. If you do not use AXIS, then the panel will be separate offline from the front end of the screen.

You can use the geometry options to resize and move the panel, for example to move it to a second screen if the system supports it. If you click the button " Display sample panel " , then the size and placement parameters will be taken into account.

GLADE VCP

The GLADE VCP fits naturally into the TOUCHY screen as they both use GTK, but by changing the GLADE VCP theme you can make them blend well with AXIS.

It uses a graphical editor to create XML files. HAL contacts are created to connect a user inside their user HAL file.

GLADE VCP also allows much more sophisticated (and complex) programming interactions that PNCconf does not currently use. (See GLADE VCP in the manual)

PNCconf has sample panels that the user can use as is or use for further development. With GLADE VCP, PNCconf will allow you to select various options on your demo display.

In the " sample options " section, select which ones you need. Zero buttons use HALUI commands, which you can edit later in the HALUI section.

Automatic Z touch also requires the classic ladder program touch and the selected sensor input. This requires a conductive contact plate and a grounded conductive tool. See here for how it works.

Section Display Options » size, position, and maximum force can be used on the standalone panel for things like placing the screen on a second monitor if the system is capable.

You can select a GTK theme that defines the basic appearance of the panel. It's usually best to have this match the interface screen. These settings will be used if you click the Show sample button. With GLADE VCP, depending on the external screen, you can choose where the panel will be displayed.

You can make it standalone, or with AXIS it can be in the center or on the right side, with Touchy it can be in the center.

Defaults and options

• Homing before MDI / start
  • If you want to be able to move the machine before homing, uncheck this box.
• Tool tip tooltip
  • Choose between prompting for a tool change screen or exporting standard signal names for a custom tool change Hal file.

6. Mesa configuration

The Mesa configuration pages allow you to use different firmware. On the main page you have selected the Mesa card, here you select the available firmware and choose which and how many components are available.

Mesa Configuration

The Parport address is only used with the Mesa Parport card, 7i43. The built-in parallel port usually uses 0x278 or 0x378, although you should be able to find the address on the BIOS page. 7i43 requires the parallel port to use the EPP mode set on the BIOS page. When using the PCI parallel port, the address can be found using the search button on the main page.

Note	Many PCI cards do not properly support EPP.

PDM PWM and 3PWM base frequency strike a balance between ripple and linearity. When using Mesa daughter cards, the card documentation should provide guidance.

Important

It is important to follow them to avoid damage and maximize performance.

 The 7i33 requires PDM and a PDM base frequency of 6 mHz The 7i29requires PWM and a PWM base frequency of 20 Khz The 7i30 requires PWM and a PWM base frequency of 20 Khz The 7i40 requires PWM and a PWM base frequency of 50 Khz The 7i48 requires UDM and a PWM base frequency of 24 Khz 

The watchdog timeout is used to set how long the MESA board will wait before turning off outputs if communication with the computer is interrupted. Please remember that Mesa uses active low outputs, which means that when the output pin is on it is low (approximately 0 volts), and if it is turned off the output is high (approximately 5 volts), make sure your equipment is safe. when it is off.

You can select the number of available components by deselecting those not in use. Not all component types are available for all firmwares.

Selecting less than the maximum number of components allows more GPIO pins. When using daughter cards, remember that you cannot deselect the pins that the card uses. For example, some firmware supports two 7i33 cards. If you only have one, you can deselect enough components to use a connector that supports the second 7i33. Components are canceled numerically, first by highest number, then in descending order without missing a number. If the components are not where you want them to be, you must use a different firmware. The firmware dictates where, what and the maximum number of components. Using custom firmware in PNCconf requires special procedures and is not always possible.

After selecting all of these options, click the Accept Component Changes button and PNCconf will update the I/O setup pages. Available connectors will only show I/O tabs, depending on the Mesa board.

7. Configuring Mesa I/O

Tabs are used to configure the input and output pins of the Mesa boards. PNCconf allows you to create your own signal names for use in custom HAL files.

Mesa 9 I/O setup0002 On this tab with this firmware, the components are configured for the 7i33 daughterboard, commonly used with closed loop servos. Note that the encoder counter and PWM driver part numbers are not listed in numerical order. This is in line with the requirements of the daughter board.
Mesa I/O C3

This tab has all GPIO pins. Pay attention to the three-digit numbers - they will correspond to the HAL output number. GPIO pins can be selected as input or output and can be inverted.

Mesa I/O C4

This tab has a mixture of steppers and GPIOs. The output and guide pins of step generators can be inverted. Note that inverting the Step Gen-A pin (output step pin) changes the timing of the step. It should match your controller's expectations.

8. Parport Configuration

Parport Configuration PNCconf

The parallel port can be used for simple I/O, just like the Mesa GPIO pins.

9. Axis configuration

Axis configuration PNCconf

This page allows you to configure and test the motor and/or encoder combination. When using a servomotor, an open loop test is available, when using a stepper motor, a tuning test is available.

Open loop test

The open loop test is important because it confirms the motor and encoder direction. The motor must move the axis in the positive direction when the positive button is pressed, and the encoder must also count in the positive direction. The movement of the axis must comply with the standards of the Machinery Manual, otherwise the AXIS graphic display will not make much sense. Note that the directions of the axes are based on the movement of the TOOL, not the movement of the table. There is no acceleration ramp when testing in open loop, so start with lower DAC numbers. By moving the axis a known distance, the encoder scaling can be confirmed. The encoder should count even without the amplifier turned on, depending on how the encoder is powered.

Warning

If the motor and encoder do not match the counting direction, the servo will run away when using PID control.

Since the PID settings cannot be tested in PNCconf at the moment, the settings are really meant to be reconfigured - enter your tested PID settings.

DAC scaling, maximum output and offset are used to adjust the DAC output.

Calculate DAC

These two values ​​are the scaling and offset factors for outputting the axis to the motor amplifiers. The second value (offset) is subtracted from the calculated output (in volts) and divided by the first value (scale factor) before being written to the D/A converters. The scale units are in volts per DAC output voltage. The units for the offset value are in volts. They can be used to linearize the DAC.

Specifically, when writing Linux output, the CNC first converts the desired output signal in quasi-SI units to raw actuator values, such as volts for an amplifier DAC. This scaling looks like this: The scale value can be obtained analytically by performing a unit analysis, i.e. the units are [output SI units] / [actuator units]. For example, on a car with a speed boost where 1 volt gives a speed of 250 mm/sec. Note that displacement units are expressed in machine units, e. g. mm/sec, and they are pre-subtracted from the read sensor. The value of this offset is obtained by finding the value of your output, which gives 0.0 for the output of the drive. If the DAC is linearized, this offset is typically 0.0.

Scale and offset can also be used to linearize the DAC, resulting in values ​​that reflect the combined effects of gain, DAC non-linearity, DAC units, etc. To do this, perform the following procedure:

• Create a calibration table for the output by driving the DAC with desired voltage and measuring result:

3
-9	-8,83
0	-0,96
1	-0,03
9	9.87
10	10.07

• Perform linear approximation by the lowest squares to get such coefficients A, B, that MES = A * desired + B
• pay attention to us that we are attention we need the raw output so that our measured output is identical to the command output. It means
  • cmd = a * desired + b
  • desired = (cmd-b) / a
• As a result, the coefficients a and b from the linear approximation can be used directly as scale and offset for the controller.

MMAX OUTPUT: maximum value for the PID compensation output written to the motor amplifier, in volts. The calculated output value is limited by this limit. The limit is applied before scaling to the original output units. The value is applied symmetrically to both plus and minus.

Tuning Test Unfortunately, the tuning test only works with stepper systems. Confirm that the direction of the axis is correct again. Then test the system by rotating the axle back and forth. If the acceleration or top speed is too high, you will lose steps. When moving, be aware that it may take some time for the axis to stop at low acceleration. The limit switches do not work during this test. You can set the pause time. This will allow you to adjust and read the dial indicator to see if you are losing steps.

Stepper Timing must be adapted to the requirements of the stepper controller. Pncconf provides some default controller timing options or allows you to customize the timing options. See Stepper_Drive_Timing for more known timings (feel free to add the ones you figured out). When in doubt, use large numbers like 5000, this will only limit the maximum speed.

Brushless Motor Control ( Brushless motor control) These parameters are used to provide low level control of brushless motors with special firmware and daughter cards. It also allows HAL sensors to be converted from one manufacturer to another. It is only partially supported and one will be needed to complete HAL connections.

PNCconf axis scale calculation

Scale parameters can be entered directly or the scale calculation button can be used for assistance . Use the checkboxes to select the appropriate calculations. Note that pulley teeth require the number of teeth, not the gear ratio. If you are satisfied with the scale, click Apply, otherwise click Cancel and enter the scale directly.

Home switches and limit switches PNCconf

Also on the schematic tab are two examples of home switches and limit switches. These are two examples of many different ways to set the reference point and limits.

Important

It is very important to start with the axis moving in the right direction, otherwise it will be very difficult to get the right return to the starting position!

Remember that the positive and negative directions refer to TOOLS, not to the table.

On a typical mill

• when the table is extended, this is the positive Y direction
• when the table moves to the left, this is the positive X direction
• when the table moves down, this is the positive direction Z
• when the spindle moves up, this is the positive direction Z

On a typical lathe

• when the TOOL moves to the right, from the chuck it is the positive direction this is the positive X direction. Some lathes have an X opposite (such as the tool on the back side), this will work fine, but the AXIS graphic display cannot reflect this.

When using homing switches and/or limit switches, LinuxCNC expects HAL signals to be true when the switch is pressed/operated. If the signal for the limit switch is wrong, then LinuxCNC will think that the machine is running at its limit all the time. If the home trailer search logic is wrong, LinuxCNC will move in the wrong direction. In fact, it will try to turn off the home switch.

Determine the position of the limit switch.

Limit switches are backup software limits in case something happens to the electronics, like a servo running away. Limit switches should be placed so that the machine does not touch the physical end of the axis movement. Remember that when moving fast, the axle will move past the point of contact. Limit switches on the machine must be in active lower position. For example, power is constantly flowing through the switches - a power loss (open switch) is triggered. Although you can connect them in another way, it is safe. May need to be inverted so that the HAL signal in LinuxCNC is at active high. - TRUE means that the switch has tripped. When running LinuxCNC, if you get a limit warning and the axis does NOT fire, inverting the signal is probably the solution. (use HALMETER to check the corresponding HAL signal, eg eg. joint.0.pos-lim-sw-in X axis positive limit switch)

Decide on the location of the home switch.

If you use limit switches, you can also use them as a home switch. A separate home switch is useful if you have a long axle that is typically used far from the limit switches, or moving the axle towards the ends creates collision problems with material. for example, a long shaft in a lathe makes it difficult to return to the home position without the tool hitting the shaft, so a separate home switch closer to the middle may be better. If you have an encoder with an index, then the home position switch acts as the home course and the index will be the actual home location.

Determine the machine coordinate zero position.

MACHINE ORIGIN is what LinuxCNC uses to refer to all user coordinate systems. I can't think of a reason why it could be in any particular location. There are only a few G codes that can access the MACHINE COORDINATE system (G53, G30 and G28). When using the tool change option on the G30, it can be convenient to have the origin at the tool change position. By convention, it's easiest to set ORIGIN on the home switch.

Determine the (final) home position (HOME POSITION)

This function simply places the caret in a permanent and comfortable position after LinuxCNC determines where ORIGIN is.

Measure / calculate the travel distances of the positive / negative axis.

Move the axis to the origin. Mark a link on the movable caliper and fixed mount (so they are in line) to move the machine to the extremes. Measure one of the distances traveled between the marks. Move the table to the other end of the path. Measure the marks again. If ORIGIN is at one of the limits, then this travel distance will be zero.(machine)

MACHINE ORIGIN

The origin is the MACHINE origin. (not the zero point where you set the cutter/material). LinuxCNC uses this dot to refer to everything else. It must be within the software. LinuxCNC uses the position of the home switch to calculate the home position (when using home switches or must be set manually if not using home switches.

Travel distance

This is the maximum distance the axle can travel in each direction. This can be measured directly from the source to the limit switch. The positive and negative travel distance must be the total travel distance.

POSITIVE TRAVEL DISTANCE

This is the distance that the axis travels from the origin to the positive travel distance or total travel minus the negative travel distance. You must set this value to zero if the origin is at the positive limit. Will always be zero or a positive number.

NEGATIVE TRAVEL DISTANCE

This is the distance the axis travels from the origin to the negative travel distance. Or the total travel minus the positive travel distance. You must set this value to zero if the origin is at the negative limit. It will always be zero or a negative number. If you forget to make it negative, PNCconf will do it internally.

HOME POSITION

This is the position where the original sequence ends. It is referenced from the source, so it can be negative or positive depending on which side of the source it is located. In the (final) home position, if you have to move in a positive direction to get to the origin, the number will be negative.

HOME SWITCH LOCATION

This is the distance from the Home switch to Origin. It can be negative or positive, depending on which side it is on. When at the home switch location, if you have to move in a positive direction to get to the starting point, the number will be negative. If you set this value to zero, then the origin will be at the location of the limit switch (plus the index lookup distance, if used).

Home point search speed

Home point search speed in units per minute.

Home search direction

Sets the home switch search direction to either negative (i.e. towards the negative limit switch) or positive (towards the positive limit switch).

Home speed reference point

Fine Home search speed in units per minute

End speed

Speed ​​used from home point position to (end) home position in units per minute. Set to 0 for maximum fast speed

Use Comp. File

Allows you to specify the file name and type of Comp. Provides complex compensation. See Section AXIS in the INI chapter. Use Backlash Compensation

Allows you to set a simple backlash compensation. Cannot be used with compensation file. See the AXIS section in the INI chapter.

AXIS

Reference Chart The charts should help to show an example of limit switches and standard axis movement directions. In this example, the Z axis was with two limit switches, the positive switch being used as the home switch. The zero point is at the negative limit. The left end of the carriage is the negative actuation pin and the right end is the positive actuation pin. We want the FINAL HOME POSITION to be 4 inches from the start on the positive side. If the carriage was moved to the positive limit, we would measure 10 inches between the negative limit and the negative trip pin.

10. Spindle configuration

If you select spindle signals, this page is available to configure spindle control.

Tooltip

Many of the options on this page will not display unless the correct option was selected on the previous pages!

Spindle configuration PNCconf

This page is similar to the axis motor configuration page.

There are some differences:

• If no stepping spindle is selected, there are no acceleration or speed limits.
• No gear or range support.
• If you have selected the VCP spindle display option, then the spindle speed bar and filter settings can be displayed.
• Spindle speed allows LinuxCNC to wait for the spindle to reach the desired speed before moving the axis. This is especially useful on lathes with a constant surface feed and a large change in speed diameter. This requires either feedback from the encoder or a digital spindle speed signal, usually connected to the VFD.
• When using encoder feedback, you can select a spindle speed scale setting that indicates how close the actual speed is to the requested speed to be considered at speed.
• When using encoder feedback, the VCP speed display may be unstable - a filter setting can be used to smooth the display. The encoder scale must be set to match the encoder counter/transmission being used.
• If you are using a single spindle encoder input, you must add the line: setp hm2_7i43.0.encoder.00.counter-mode 1 (change board name and encoder number to suit your requirements) to the user HAL file. See the Encoders section of Hostmot2 for more information on counter mode.

11. Advanced Options

This section allows you to configure HALUI commands and download classic programs and Ladder program examples. If you have selected GLADE VCP options, such as axis zeroing, commands will be displayed. See the HALUI chapter for more information on using custom settings. There are several options for ladder logic. The Estop program allows an external ESTOP switch or GUI to issue Estop. It also has a synchronized grease pump signal. Automatic Z touch is done with a flip plate, GLADE VCP touch button and HALUI specific commands to set current user source to zero and quick reset. The Modbus serial interface program is essentially an empty template program that sets up the classic interface for the Modbus serial interface. See the Classicladder chapter in the manual.

Additional PNCconf Parameters

12. HAL Components

On this page you can add additional HAL components that may be needed for custom HAL files. Thus, there is no need to manually edit the main HAL file while still allowing the user the required components.

PNCconf HAL Components

The first choice is the components that pncconf uses internally. You can configure pncconf to load additional component instances for your custom HAL file.

Select the number of instances your user file will need, pncconf will add what it needs after them.

This means that if you need 2 and pncconf needs 1, pncconf will load 3 instances and use the last one.

Custom component commands

This selection will allow you to load HAL components that pncconf does not use. Add the loadrt or loadusr command under heading load command. Add addf command under heading Command thread. Components will be added to the stream between reading inputs and writing outputs in the order you write them in command of stream .

13. Advanced use of PNCconf

PNCconf does its best to allow user flexibility. PNCconf supports custom signal names, custom component loading, custom HAL files, and custom firmware.

There are also signal names that PNCconf always provides regardless of the options selected for user HAL files. Some people think that most of the settings should work regardless of whether you later choose other options in PNCconf.

In the end, if the settings are out of scope for PNCconf, you can use PNCconf to create a basic configuration, or use one of the sample LinuxCNC configurations and just manually edit it the way you want.

Custom signal names

If you want to connect the component to something in a custom HAL file, write a unique signal name in the combo box. Some components will add endings to your custom signal name:

User-defined signal names

The Hal Components page can be used to download components required by the user for configuration.

Loading custom firmware

PNCconf looks for firmware on the system and then looks for an XML file that it can convert to something it understands. These XML files are only supplied for officially released firmware from the LinuxCNC team. To use custom firmware, you need to convert it to an array that PNCconf understands and add the path to it in the PNCconf configuration file. By default, this path looks on the desktop for a folder named custom_firmware and a file named firmware.py.

A hidden preferences file is located in the user's home file called .pncconf-preferences and requires hidden files to be shown in order to be seen and edited. The contents of this file can be seen when PNCconf is loaded for the first time - click the help button and see the output page.

Custom HAL files

There are four custom files you can use to add HAL commands:

• custom.hal is for HAL commands that don't need to be run after the GUI has loaded. It runs after the HAL file with the configuration name.
• custom_postgui.hal is for commands to be executed after AXIS is loaded or PYVCP standalone display is loaded.
• custom_gvcp.hal is for commands to be run after the Glade VCP is loaded.
• shutdown.hal is for commands to be run on LinuxCNC controlled shutdown.

Machine control setup via LPT parallel port. Stepconf

LinuxCNC can control a wide range of hardware using many different hardware interfaces. Stepconf is a program that generates configuration files for LinuxCNC for a specific class of CNC machines: those controlled via standard parallel port and controlled by signals like step & direction .

Stepconf is installed when installing LinuxCNC and is located in the CNC menu.

Stepconf puts a file in the linuxcnc/config directory to store options for each configuration you create. When you change something, you need to select the file that matches the name of your configuration. The file extension is .stepconf.

The Stepconf Wizard works best with a screen resolution of at least 800 x 600.

Stepconf start page

Stepconf start page
• Create New - Creates a new configuration.
• Modify - change an existing configuration. After selecting this option, a file selection pop-up appears, in which you can select the .stepconf file to modify. If you have made any changes to the main .hal or .ini file, they will be lost. The Stepconf wizard will not modify custom.hal and custom_postgui.hal modifications. Stepconf will highlight the last created configuration file.
• Import - Import the Mach config file and try to convert it to a linuxcnc config file. After the import, you will go through the stepconf pages to confirm/change the entries. The original mach xml file will not be modified.

These settings will be written to the configuration file for the next stepconf run.

• Create Desktop Shortcut - a link to the files will be placed on your desktop.
• Create Desktop Launcher - This will place a launcher on the desktop to launch your application.
• Create Simulated Hardware - This allows you to create a configuration for testing even if you don't have real hardware.

Stepconf Basic Information

Stepconf Basic Information
• Machine Name - Select a name for your machine. Use only uppercase letters, lowercase letters, numbers, - and _.
• Axis Configuration - Select XYZ (Mill), XYZA (4-Axis Mill), or XZ (Lathe).
• Machine Units - select inches or mm. All subsequent entries will be in the selected units. Changing this setting also changes the default values ​​in the Axes section. If you change this after selecting values ​​in any of the axes sections, they will be overwritten with the default values ​​of the selected units.
• Driver Type - If you have one of the stepper motor drivers listed in the drop-down list, select it. Otherwise select " Other", find the timing values ​​in your driver data sheet and enter them as nanoseconds in " Driver Timing Settings " . If the value in the datasheet is in microseconds, multiply it by 1000. For example, enter 4.5 µs as 4500 ns.

A list of some popular drivers along with their times can be found on the LinuxCNC.org Wiki under Stepper Drive Timing.

Additional signal processing or isolation, such as optocouplers and RC filters on output boards, may impose their own timing restrictions in addition to those of the driver. You may need to add time to disk requirements to account for this.

The LinuxCNC configuration selector has already configured configurations for Sherline.

• Step Time Pulse step in nanoseconds. If you are unsure about this setting, a value of 20,000 will work for most machines.
• Step Space is the minimum time between step pulses in nanoseconds. If you are unsure about this setting, a value of 20,000 will work for most machines.
• Direction Hold - how long the direction indicator is held after the direction change in nanoseconds. If you are unsure about this setting, a value of 20,000 will work for most machines.
• Direction Setup - How long before the direction changes after the last step pulse in nanoseconds. If you are unsure about this setting, a value of 20,000 will work for most machines.
• One / Two Parport - Select how many parallel ports to configure.
• Base Period Maximum Jitter - Enter the delay test result here. To start the delay test, press the button Test Base Period Jitter . For more information, see the Checking Delay section.
• Max Step Rate - Stepconf automatically calculates the maximum step rate based on the driver characteristics entered and the latency test result.
• Min Base Period - Stepconf automatically determines the minimum base period based on the entered driver characteristics and the latency test result.

Delay test

During the test, load the computer . Move windows around the screen. Climb on the Internet. Copy some large files to disk. Turn on the music. Run an OpenGL program such as glxgears. The idea is to test the PC while the latency test checks what the worst numbers are. Run the test for at least a few minutes. The longer you run the test, the better it will catch events that may occur at shorter intervals. This is a test for your computer only, so you don't need to connect any hardware to run it.

Warning: Do not attempt to start LinuxCNC while the delay test is running.

Stepconf latency test

Latency is the time it takes for the PC to stop its actions and respond to an external request. In our case, the request is a periodic heartbeat, which serves as a timing reference for step pulses. The shorter the delay, the faster you can start the heartbeat and the faster and smoother the step impulses will be.

Latency is more important than processor speed. CPU is not the only factor that determines latency. Motherboards, video cards, USB ports, SMI issues, and a number of other things can affect latency.

Fixing real-time problems caused by SMI in Ubuntu

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

The important numbers are max jitter . In the example above, 9075 nanoseconds or 9.075 microseconds is the highest jitter. Write down this number and enter it in the field " max jitter" base period.

If your max jitter is less than about 15-20 microseconds (15000-20000 nanoseconds), the computer should give very good results with software stepping. If the maximum latency is greater than 30-50 microseconds, you can still get good results, but your maximum cadence can be a little disappointing, especially if you are using microstepping or very fine pitch leadscrews. If the numbers are 100 µs or more (100,000 nanoseconds), then the PC is not a good candidate for software stepping. Numbers over 1 millisecond (1000000 nanoseconds) mean that the PC is not a good candidate for LinuxCNC, whether you use software stepping or not.

Parallel port setting

Parallel port setting

You can specify the address in hexadecimal format (often 0x378) or as the Linux default port number (possibly 0).

For each pin, select the signal that matches your parallel port pinout. Enable the invert checkbox if the signal is inverted (0V for true/active, 5V for false/inactive).

• Output pinout presets - Automatic setting of pins 2 to 9 according to Sherline standard (direction to pins 2, 4, 6, 8) or Xylotex standard (direction to pins 3, 5, 7, 9).
• Inputs and Outputs - If the input or output is not used, set the parameter to Unused .
• B External E Stop - it can be selected from the drop-down list of input contacts. A typical E Stop circuit uses all normally closed contacts.
• Homing & Limit Switches - These can be selected from the input contact drop-down list for most configurations.
• Charge Pump - If your driver board requires a charger signal, select " Charge Pump " from the drop-down list for the output pin you want to connect to the charge input. The charger output is connected to the main thread using Stepconf.

Parallel Port 2 Setup

Parallel Port 2 Setup

The second parallel port (if selected) can be configured and its pins are assigned on this page.
Unable to select pitch and direction signals.
You can select an input or output to maximize the number of available input/output contacts.
You can specify the address in hexadecimal format (often 0x378) or as the default port number on Linux (possibly 1).

Axis Configuration

Stepconf Axis Configuration
• Steps Per Revolution Motor is the number of full steps per revolution. If you know how many degrees per step the motor has (for example, 1.8 degrees), divide 360 ​​by degrees per step to find the number of steps per revolution of the motor.
• Driver Microstepping is the number of microstepping performed by the driver. Enter 2 for a half step.
• Pulley Ratio - If your machine has pulleys between the motor and lead screw, enter the ratio here. If not, enter 1:1 .
• Leadscrew Pitch — Enter the lead screw pitch here. If you selected inches , enter the number of threads per inch. If you selected millimeters , enter the number of millimeters per revolution (for example, enter 2 for 2 mm/rev). If the machine moves in the wrong direction, enter a negative number here instead of a positive number, or reverse the guide pin for the axis.
• Maximum Velocity - Enter the maximum speed of the axis in units per second.
• Maximum Acceleration - The correct values ​​for these elements can only be determined experimentally. See Finding the maximum speed to set the speed and Finding the maximum acceleration to set the acceleration.
• Home Location is the position to which the machine moves after completing the homing procedure for this axis. For machines without home switches, this is where the operator manually moves the machine before pressing the home button. If you combine the home and limit switches, you must move the switch to the home position or you will get a joint limit error.
• Table Travel is the travel range of this axis depending on the origin of the machine. The home location must be within table travel and not be the same as one of the table travel values.
• Home Switch Location is the location where the home switch activates or deactivates relative to the home point of the machine. This item and the two below only appear if home switches have been selected in the parallel port pinout. If you combine the home and limit switches, the position of the home switch cannot be the same as the home, otherwise you will get a joint limit error.
• Home Search Velocity The speed used when searching for the home switch. If the switch is near the end of travel, this speed must be selected so that the axle can decelerate to a stop before it reaches the end of travel. If the switch is only closed for a short range of travel (instead of being closed from the actuation point to one end of travel), this speed should be chosen so that the axle can decelerate to a stop before the switch opens again, and should always start from on the same side of the switch. If the machine is moving in the wrong direction at the beginning of the homing procedure, cancel the home search speed .
• Home Latch Direction - Select Same, to disengage the axis from the switch, then approach it again at very low speed. The second time the switch is turned on, the initial position is set. Select Opposite, to make the axis disengage from the switch again, and when the switch opens, the home position is set.
• Time to accelerate to max speed - time to reach maximum speed, calculated based on maximum acceleration and maximum speed .
• Distance to accelerate to max speed Distance to accelerate to max speed from standstill.
• Pulse rate at max speed - The information is calculated based on the values ​​entered above. The highest maximum speed pulse rate determines BASE_PERIOD . Values ​​above 20000 Hz may cause slow response times or even freezes (the fastest usable heart rate varies by computer)
• Axis SCALE - The number to be used in the [SCALE] ini file setting. This is the number of steps per user unit.
• Test this axis - a window will open in which you can test for each axis. It can be used after filling in all the information for that axis.

Test axis

Test axis

Test this axis is a basic tester that only outputs pitch and direction signals to try different values ​​for acceleration and speed.

Finding the maximum speed

Start with a little acceleration and the speed you hope to achieve. Use the available buttons to move the axis closer to the center of movement. Be careful, because with a low acceleration value, the axis can travel a surprising distance to slow down to a complete stop.

After measuring the available distance, enter the safety distance in the test area, bearing in mind that the motor may start moving in an unexpected direction after stopping. Then click Run. The machine will move forward and backward on that axis. In this test, it is important that the combination of acceleration and test area allows the car to reach the selected speed and cruise for at least a short distance - the longer the distance, the better this test. Formula d = 0.5 * v * v/a gives the minimum distance required to reach the given speed with the given acceleration. If it is convenient and safe to do so, push the table against the direction of travel to simulate cutting forces. If the machine slips, reduce speed and run the test again.

If the machine does not stop, turn off the " Run" button . The axis now returns to its original position. If the position is not correct, the axis has stalled or lost steps during the test. Reduce the speed and run the test again.

If the machine does not move, stops or loses steps, no matter how low you turn the speed, check the following:

• Proper stepping signal timing
• Proper pinout, including invert step pins
• Correct, good shielded wiring
• Physical problems with the motor, motor coupling, lead screw, etc.

Once you have found the speed at which the axle does not stop or lose steps during this test procedure, reduce it by 10% and use her as maximum speed axis. Looking for maximum acceleration

Using the maximum speed you found in the previous step, enter the acceleration value to test. Using the same procedure as above, increase or decrease the acceleration value as needed. In this test, it is important that the combination of acceleration and test area allows the car to reach the selected speed. Once you find a value at which the axis does not stop or lose steps during this test procedure, decrease it by 10% and use it as the maximum axis acceleration.

LinuxCNC Spindle Configuration Stepconf

LinuxCNC Spindle Configuration Stepconf

This page only appears if " Parallel Port Pin Assignment " page has " Spindle PWM" selected for one of the outputs.

Spindle speed control

If the pinout shows spindle PWM , the following information must be entered:

• PWM speed - Carrier frequency PWM signal per spindle. Enter 0 for PDM mode, which is useful for generating an analog control voltage. Refer to the documentation for the spindle controller for the correct value.
• Speed ​​1 and 2, PWM 1 and 2 - The generated configuration file uses a simple linear relationship to determine the PWM value for a given RPM value. If the values ​​are unknown, they can be determined. For more information, see Spindle Calibration Definition.

Motion synchronized with the spindle

When the corresponding signals from the spindle encoder are connected to LinuxCNC via HAL, LinuxCNC supports threading on the lathe. These signals are:

• Spindle Index is the pulse that occurs once per spindle revolution.
• Spindle Phase A is the pulse that occurs at several equidistant locations as the spindle rotates.
• Spindle Phase B (Optional) is the second pulse that occurs but is offset from spindle phase A. The benefits of using both A and B are direction detection, increased noise immunity, and increased resolution.

If spindle phase A and spindle index appear on the pinout, the following information must be entered: set speed before feed starts.

• Speed ​​Display Filter Gain - setting to adjust the stability of the visual display of the spindle speed.
• Cycles per revolution This option is only available if the input is set to spindle phase A.
• Maximum speed in thread is the maximum spindle speed used when threading. High spindle speed or high resolution spindle encoder requires a low value of BASE_PERIOD .