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Question #: 3522

Question: I'm having trouble getting Mach3 to recognize my limit switches. I've eliminated everything back to the breakout board. I can directly connect Input 10 to GND on the breakout board while Mach3 is in autorecognize mode and Mach3 doesn't acknowledge anything.

Current Solution

Have you tried a different input pin?

Customer response:
I've tried all pins: 10, 11, 12, and 13. I get the same non-response in each case.

Recommended action
There may be a problem with the board. If you are using our parallel breakout board, we can ship you a replacement (call us), otherwise, you will need to determine the problem with the vendor of the breakout board you are using.

Additional Information:
I have tried 3 different breakout boards from 3 different providers and they all do the same thing My limit switches are microswitches wired NC with each axis wired to the BO Board. I have checked each circuit and all is OK to the BO board. each circuit has continuity at the board and when any switch is pressed the circuit breaks. Mach 3 does not recognise that the switches are even there. They are configured as active low Do you have a suggestion.

Respond:

Other Possible Solutions to this Question

  • I decided to connect 5v directly to my usb breakout board, but when I plug the usb cable in, the planetcnc app does not recognize it and the green status light does not come on. I've confirmed that it is getting exactly 5v, and the jumper is removed.

    We apologize for this issue, we had a mistake with the labeling on the board! If you reverse the GND, and the 5V on the Alt-power the power will work and the board will be recognized by Planet-CNC.

    Once again we apologize for this issue!

    User response:
    Thanks - glad it is an easy fix! You guys should update the docs - perhaps on the item description for the future confused.

    Buildyourcnc Team:
    We updated the product page to reflect this error. Many thanks!

    Response:
    FYI - to anyone who reads this - reversing the polarity on the 5v alt power will indeed damage the board, though not immediately.

    Click the link to add information to this solution:
    I decided to connect 5v directly to my usb breakout board, but when I plug the usb cable in, the planetcnc app does not recognize it and the green status light does not come on. I've confirmed that it is getting exactly 5v, and the jumper is removed.

  • I have nearly completed the CNC machine from the book, but I am using it with a USB breakout board, and have no idea how to wire the 6 limit switches to the board. I'm having difficulty following the diagram on the USB breakout board screen. Can someone please help me?

    Sure, the USB interface has a place for 4 axes of limit switches.

    Each axis can have two limit switches: one for the ++ (positive) end and one for the -- (negative) end. The positive end would be the limit switch at the end of the machine that, say the machine has a 4'x8' area, reaches a bit after the 8 foot mark. The negative end would be the limit switch behind the 0 foot location behind the origin. If the origin is in the middle, the negative would be at a little more than the -4 foot end and the positive would be at a bit more than the +4 foot end. Note that you can have more than one switch on each pin where the NC is connected in serial fashion and the NO is connected in parallel fashion (this can be seen on the diagram in the multiple limits switch section). The software configurations for the limits switches are under File -> Settings -> Limit.

    A typical limit switch has three connections on it. These connections consist of COM (common), NC (normally closed) and NO (normally open). The COM would generally go to GND and the NC or the NO would go to the pin. If the NC is used, then the the switch is constantly connected until the switch is pushed (engaged) then the connection from the pin to gnd is broken (open). Use the settings in software to set whether in NC or NO configuration.

    Let me know if this information was helpful (or not) by adding information to this question. Thanks.

    User response:
    Thank you very much for this helpful information. I'm still a little fuzzy on how the 6 limit switches physically connect to each other and to the USB breakout board. You've stated one switch (home) goes to positive and another switch (limit) goes to negative. Are all the GND prongs from all 6 switches connected to each other and going to GND on the breakout board, or no? And the NC prongs, how exactly are they connected to each other? And to the board? There has to be a diagram somewhere shows this visually, no? I don't know how to wire the switches in series or in parallel. I have already physically installed all the switches on the machine and ran the wires to where the board is. Now I just need to know where to plug these wires into the board. Also, taking into consideration that I'm using the Planet CNC software, the only settings I have pertaining to limit switches is "Enable/Disable" for each axis, and the actual limit for each axis. Nothing about NC or NO. Is that only in Mach3?
    Thank you.

    buildyourcnc response:
    On the USB interface, the COM on the switch connects to GND and the NC or NO connects to the input pin (i.e. x++, y--, etc.)

    Limit switch configuration is rather difficult to understand, especially with series and parallel. You can think of series as a single wire going from GND to the axis letter input terminal (i.e. X++ or X--). If the wire is broken, then the circuit is open (or the switch is engaged in a normally closed scenario). Normally closed is like an actual wire, and when engaged, the switch "opens" (breaks the wire). This is why we recommend in some systems that you can put many switches in series on a single pin. When one of the switches is engaged (breaking the connection) then the entire circuit of switches is broken and the machine stops.

    In a parallel scenario, the state of the circuit is always broken until the one of the switches is engaged and the circuit is then closed or connected. The topology looks like a ladder. All the switches connect to both sides of the ladder and the switches are like the runs of the ladder (the horizontal bars that the feet are placed while climbing). Imagine all of the switches broken in this scenario (normally open). It would be like the ladder could be split in two, but if one of the ladder runs (switches) is closed by engaging it, then that run would connect both sides of the ladder and the two sides of the ladder would have a connection.

    There is a diagram on the USB page of the various limit switch configurations. If you need more information (visual and/or otherwise), please let us know and we will immediately add that information to benefit everyone.

    Click the link to add information to this solution:
    I have nearly completed the CNC machine from the book, but I am using it with a USB breakout board, and have no idea how to wire the 6 limit switches to the board. I'm having difficulty following the diagram on the USB breakout board screen. Can someone please help me?

  • LIMIT SWITCHES FOR AXIS. THE PRINT SHOWS THAT YOU CAN WIRE LIMITS EITHER N.O. OR N.C. SO IF THIS IS CORRECT I WOULD NEED TO TELL BOARD IN SOFTWARE HOW LOOK AT THESE LIMITS, I'M GOING GET AN INPUT LOOSE DEPEND ON IT.

    BYCNC Response:
    This is correct. You will need to use a method appropriate for the software you are using. Also remember that NC switches are typically wired in series, while NO switches are normally wired in parallel.

    User Response:
    I am using the cnc planet software for your USB board. Are the limit configurations in this software?

    BYCNC Response:
    Yes, Planet CNC software is compatible with the use of limit switches. Configuration information will depend on your specific application. You can view Planet CNC's information here: http://www.planet-cnc.com/files/CNCUSBController.pdf

    Click the link to add information to this solution:
    LIMIT SWITCHES FOR AXIS. THE PRINT SHOWS THAT YOU CAN WIRE LIMITS EITHER N.O. OR N.C. SO IF THIS IS CORRECT I WOULD NEED TO TELL BOARD IN SOFTWARE HOW LOOK AT THESE LIMITS, I'M GOING GET AN INPUT LOOSE DEPEND ON IT.

  • Hey Guys, I have a brand new redleaf and 5x. In the final stages of wiring and wondering a few things. Can I connect the Mach3 USB board V+ V- to my frequency inverter (type YL600-2s-2k20)? If so where? Will your upcoming (part 2)video deal with this as well as final connections for limit switches and stop button? Merry Christmas!

    Yes, the Mach3 USB board has two terminals that require 24V connection. Most VFDs have a 24V output that can be used to power this part of the Mach3 USB board.

    The V+ and V- on the Mach3 USB is not absolutely necessary to operate the CNC machine/router. The V+ and V- of the Mach3 USB board powers the outputs, inputs, and spindle's speed and control.

    Here is the Mach3 USB link for more information:
    https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach3-USB-Board

    The new YL600 VFD we have in stock may not have this 24V output. There is a 12V terminal, but I have not tested that terminal if it outputs 12V, or if it is a 12V input. If you are only conecting limit switches to the Mach3 USB and need to power that portion, 12V will be sufficient.

    I will delve into these aspects in far more detail on video.

    Thanks and Merry Christmas to you as well!

    Click the link to add information to this solution:
    Hey Guys, I have a brand new redleaf and 5x. In the final stages of wiring and wondering a few things. Can I connect the Mach3 USB board V+ V- to my frequency inverter (type YL600-2s-2k20)? If so where? Will your upcoming (part 2)video deal with this as well as final connections for limit switches and stop button? Merry Christmas!

  • Limit switches for axis. The print shows that you can wire the limits either n.o. or n.c. so if this is correct I would need to tell the board in the software how to look at these limits, I'm either going to get an input or loose an input depend on how i wire it.

    BYCNC Response:
    This is correct. You will need to use a method appropriate for the software you are using. Also remember that NC switches are typically wired in series, while NO switches are normally wired in parallel.

    User Response:
    I am using the cnc planet software for your USB board. Are the limit configurations in this software?

    BYCNC Response:
    Yes, Planet CNC software is compatible with the use of limit switches. Configuration information will depend on your specific application. You can view Planet CNC's information here: http://www.planet-cnc.com/files/CNCUSBController.pdf

    Click the link to add information to this solution:
    Limit switches for axis. The print shows that you can wire the limits either n.o. or n.c. so if this is correct I would need to tell the board in the software how to look at these limits, I'm either going to get an input or loose an input depend on how i wire it.

  • I need wiring instructions for the breakout board you sent yesterday. It is not like the one in the videos and I don't know where to connect the 5V. No data sheet or anything.
  • I am attempting to set up limit switches on the 5 axis parallel breakout board that came with my BlackFoot kit. The output pins are driving the motors perfectly, but I can't figure out the input pins. With one lead in the 5V pin and one lead testing the input pins, my multimeter reads 0V for all of the input pins. Shouldn't those circuits be +5V? Where am I going wrong?

    When wiring the limit switches to our BoB(breakout board), depending in the older model or our revised version (https://www.buildyourcnc.com/item/electronicsAndMotors-parallel-breakout-relay#prettyPhoto/0/), the older version will need the COM (limit switch) connected to 5V and the NO/NC to your input pin, but with our newer version you will use GND(ground instead of 5V) to common and the same for NO/NC but the setup in the mach3/confi/ports&pins/ is still the same.

    Here is a tutorial where you can see how to set up the limit switches correctly (with our older parallel BoB): Part 1:(

    ), Part 2:(
    )

    Click the link to add information to this solution:
    I am attempting to set up limit switches on the 5 axis parallel breakout board that came with my BlackFoot kit. The output pins are driving the motors perfectly, but I can't figure out the input pins. With one lead in the 5V pin and one lead testing the input pins, my multimeter reads 0V for all of the input pins. Shouldn't those circuits be +5V? Where am I going wrong?

  • I have a breakout board and it appears that the pin 12 connection has failed: when i move my limit switches to pin 11 they work; they don't work on pin 12. Do i need a new breakout board?

    For safety's sake I would recommend a new board because they are inexpensive compared to the electronics that they support. Alternatively, it's possible that the one dead pin is a simple fix, such as a bad connection or solder joint; if you feel comfortable making those repairs then it could be worthwhile to check. Finally, if you are not using all the input pins, you could continue to operate the limit switch on pin 11 and hope for the best.

    Click the link to add information to this solution:
    I have a breakout board and it appears that the pin 12 connection has failed: when i move my limit switches to pin 11 they work; they don't work on pin 12. Do i need a new breakout board?

  • When the machine hits the limits it stops but the switch is still tripped so clicking the Mach3 RESET button doesn't do anything. How am I supposed to get the machine to move off of the limit switch so I can continue working?

    If you select the Settings Page and select or tick Auto Limit Override - this will allow you to back off the switch.

    Additional Information:
    limit and home switch

    Click the link to add information to this solution:
    When the machine hits the limits it stops but the switch is still tripped so clicking the Mach3 RESET button doesn't do anything. How am I supposed to get the machine to move off of the limit switch so I can continue working?

  • I purchased limit switches from you mounted them on my machine and wire them to the breakout for using pin 12 and the ground on the breakout board, after a few minutes I got a message about a limit switch trip. Am I supposed to use the extra outport on the board instead of the ground?

    Sure, the USB interface has a place for 4 axes of limit switches.

    Each axis can have two limit switches: one for the ++ (positive) end and one for the -- (negative) end. The positive end would be the limit switch at the end of the machine that, say the machine has a 4'x8' area, reaches a bit after the 8 foot mark. The negative end would be the limit switch behind the 0 foot location behind the origin. If the origin is in the middle, the negative would be at a little more than the -4 foot end and the positive would be at a bit more than the +4 foot end. Note that you can have more than one switch on each pin where the NC is connected in serial fashion and the NO is connected in parallel fashion (this can be seen on the diagram in the multiple limits switch section). The software configurations for the limits switches are under File -> Settings -> Limit.

    A typical limit switch has three connections on it. These connections consist of COM (common), NC (normally closed) and NO (normally open). The COM would generally go to GND and the NC or the NO would go to the pin. If the NC is used, then the the switch is constantly connected until the switch is pushed (engaged) then the connection from the pin to gnd is broken (open). Use the settings in software to set whether in NC or NO configuration.

    Let me know if this information was helpful (or not) by adding information to this question. Thanks.

    User response:
    Thank you very much for this helpful information. I'm still a little fuzzy on how the 6 limit switches physically connect to each other and to the USB breakout board. You've stated one switch (home) goes to positive and another switch (limit) goes to negative. Are all the GND prongs from all 6 switches connected to each other and going to GND on the breakout board, or no? And the NC prongs, how exactly are they connected to each other? And to the board? There has to be a diagram somewhere shows this visually, no? I don't know how to wire the switches in series or in parallel. I have already physically installed all the switches on the machine and ran the wires to where the board is. Now I just need to know where to plug these wires into the board. Also, taking into consideration that I'm using the Planet CNC software, the only settings I have pertaining to limit switches is "Enable/Disable" for each axis, and the actual limit for each axis. Nothing about NC or NO. Is that only in Mach3?
    Thank you.

    buildyourcnc response:
    On the USB interface, the COM on the switch connects to GND and the NC or NO connects to the input pin (i.e. x++, y--, etc.)

    Limit switch configuration is rather difficult to understand, especially with series and parallel. You can think of series as a single wire going from GND to the axis letter input terminal (i.e. X++ or X--). If the wire is broken, then the circuit is open (or the switch is engaged in a normally closed scenario). Normally closed is like an actual wire, and when engaged, the switch "opens" (breaks the wire). This is why we recommend in some systems that you can put many switches in series on a single pin. When one of the switches is engaged (breaking the connection) then the entire circuit of switches is broken and the machine stops.

    In a parallel scenario, the state of the circuit is always broken until the one of the switches is engaged and the circuit is then closed or connected. The topology looks like a ladder. All the switches connect to both sides of the ladder and the switches are like the runs of the ladder (the horizontal bars that the feet are placed while climbing). Imagine all of the switches broken in this scenario (normally open). It would be like the ladder could be split in two, but if one of the ladder runs (switches) is closed by engaging it, then that run would connect both sides of the ladder and the two sides of the ladder would have a connection.

    There is a diagram on the USB page of the various limit switch configurations. If you need more information (visual and/or otherwise), please let us know and we will immediately add that information to benefit everyone.

    Click the link to add information to this solution:
    I purchased limit switches from you mounted them on my machine and wire them to the breakout for using pin 12 and the ground on the breakout board, after a few minutes I got a message about a limit switch trip. Am I supposed to use the extra outport on the board instead of the ground?

  • I want to add limit switches but I have no connections on the breakout board. Can I use a usb interface board for the limit switches as well as the parallel port for the running?

    You can add a limit switch to either the USB or the parallel board. Please refer to the product pages for these items to view wiring diagrams.

    Click the link to add information to this solution:
    I want to add limit switches but I have no connections on the breakout board. Can I use a usb interface board for the limit switches as well as the parallel port for the running?

  • I want to add limit switches but I have no connections on the breakout board. Can I use a usb interface board for the limit switches as well as the parallel port for the running?

    You can add a limit switch to either the USB or the parallel board. Please refer to the product pages for these items to view wiring diagrams.

    Click the link to add information to this solution:
    I want to add limit switches but I have no connections on the breakout board. Can I use a usb interface board for the limit switches as well as the parallel port for the running?

  • [575] I have finally got my limit switches wired and working - thank you. Can they also used as homing switches and if so it it just a question of looping the two inputs on the board i.e. the limit and home terminals IN2 to IN3

    You will want to connect the homing switches (which may also serve as your near limit switches) to different input terminals. It's ok to add more limit switches with the home switches, but each home should be on independent inputs. For example, connect home X and any other limit switch to IN1, connect home Y and any other limit switch to IN2, and so on. This will allow you to properly use the "ref all home" button in Mach3.

    Additional Information:


    Additional Information:
    In the instructions (diagram 1) you show all the home switches connected in parallel? But here you say they need to each have their own inputs. "You will want to connect the homing switches (which may also serve as your near limit switches) to different input terminals." I dont see how the second and third axis can go home if the first axis has already closed the parallel circuit unless they back off a bit until the switch opens up again before the next axis goes to home? My machine has no limit switches so I assume they are home switches.

    Click the link to add information to this solution:
    [575] I have finally got my limit switches wired and working - thank you. Can they also used as homing switches and if so it it just a question of looping the two inputs on the board i.e. the limit and home terminals IN2 to IN3

  • I am getting a certain amount of offset on my 2nd machining pass on my blackfoot. I am preparing to go back and make sure everything is tight, however is it possible to overtighten the chains and sprockets. Is there a general rule of thumb to increase rigidity?

    The chain should be tensioned the same on both sides, and you should have some slack and not have it too tight. The bearings should be tightly secured as well. There is another probable cause, which is the rod, where the sprocket is tighten to. Since the rod is circular the sprocket screws, cannot securely tighten the rod, which you can file where the 2 screws rest to have a flat surface or if you have a welder you can tack weld the sprocket to the rod.

    Click the link to add information to this solution:
    I am getting a certain amount of offset on my 2nd machining pass on my blackfoot. I am preparing to go back and make sure everything is tight, however is it possible to overtighten the chains and sprockets. Is there a general rule of thumb to increase rigidity?

  • [575] I had limit switches working and on input 2. Now looking at Mach 3 diagnostics, Input 2 is continuously on and triggers limit stop. I removed all input 2 so the machine can run. Rebooted all. Anyway to reset Input on card?
  • Please provide detailed instructions on how to connect limit switches to CNC USB BOARD. I can not find instructions anywhere. I am new to cnc world and really need help. Thanks

    The USB Interface page: https://buildyourcnc.com/item/electronicsAndMotors-electronic-component-USB-Controller-Breakout

    On this page, there is a datasheet that explains the connection schemes for the limit switches on step 1 of the instructions. The datasheet explains single and multiple switch configurations and parallel/serial connections schemes for the NO/NC (Normally Open/Normally Closed states).

    If there is further information you need, please reply on this FAQ.

    Click the link to add information to this solution:
    Please provide detailed instructions on how to connect limit switches to CNC USB BOARD. I can not find instructions anywhere. I am new to cnc world and really need help. Thanks

  • I have a 2000 WK 11–3 Z limit switches going to A c10r10 breakout board . Can I also use them as my home position as well. I need The wiring configuration

    No, you should not have received two parallel breakout boards in your CNC kit. You can return the extra item using standard shipping with COD. Our apologies for the confusion and the inconvenience.

    I will answer the other question as another FAQ. Please check the Customer Service page to see the answer to that question.

    If you have difficulty finding the answer, here is a link:
    https://www.buildyourcnc.com/FAQ/13636

    Click the link to add information to this solution:
    I have a 2000 WK 11–3 Z limit switches going to A c10r10 breakout board . Can I also use them as my home position as well. I need The wiring configuration

  • I am having trouble connecting the cambam program with my Mach3 to my 4X8 Blackfoot CNC machine. Where can I get help on this issue. Have had my machine since 2015 and have not been able to use it. Thank you

    CamBam specifically creates the g-code (machining operations) instructions to be loaded into Mach3. Make sure in your CamBam g-code file parameters, you are using the Mach3 post processor. If you have already done this, let me know. If you are not sure how to do this, let me know.

    Click the link to add information to this solution:
    I am having trouble connecting the cambam program with my Mach3 to my 4X8 Blackfoot CNC machine. Where can I get help on this issue. Have had my machine since 2015 and have not been able to use it. Thank you

  • Mach3 doesn't take MPG input from USB RnRMotion board. While running Mach3 "Manage plugins">"RnRMtion control panel. I can see the signals from the hand controller changing, Mach3 diagnostics show nothing.

    There are many ways to wire an emergency stop switch. The simplest, and arguably the most certain, way is to wire the switch into the incoming power so that throwing the switch kills all power to every part of the machine. Here is a diagram showing how a customer wired such a switch on their blackTooth laser which you could adapt to your needs. http://www.buildyourtools.com/phpBB3/viewtopic.php?f=12&t=4872

    Alternatively, you could use an input pin on your USB board. The wiring would depend on whether and how you might be using limit switches (single or multiple switches; normally open or normally closed). Our website datasheet for the USB board is at https://buildyourcnc.com/item/electronicsAndMotors-electronic-component-USB-Controller-Breakout#prettyPhoto/2/ and shows how to configure the switches for each set up. If you use this method, you'd essentially wire the e-stop as a limit switch.

    Click the link to add information to this solution:
    Mach3 doesn't take MPG input from USB RnRMotion board. While running Mach3 "Manage plugins">"RnRMtion control panel. I can see the signals from the hand controller changing, Mach3 diagnostics show nothing.

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