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Question #: 3565

Question: have a parallel BOB, limit switches get triggered constantly when power is plugged in.

Current Solution

How do you have the limit switches wired?

Respond:

Other Possible Solutions to this Question

  • How can I convert from Xylotex to yours, four axis with limit switches. Have parallel PC and steppers on machine.

    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 respond:
    How can I convert from Xylotex to yours, four axis with limit switches. Have parallel PC and steppers on machine.

  • 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 respond:
    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 respond:
    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?

  • parallel break out board is not working-relay keeps switching my computer off when I power up

    Do you have anything connected to the relay?

    Additional Information:
    is the relay controlled by a pinout on the BoB?

    Additional Information:
    Nothing is attached to the relay pins I am only using 2 and 3 and 5v for x driver and led indicator, 4 and 5 and 5v for y driver and led indicator, and 6 to fire the laser and the led indicator. I am also using a 5v out for the laser power control circuit and one pin of the 5k pot. Ground is shared on the laser power supply, the cnc power supply and the x and y driver. I am using the computer motherboard supplied by Buildyoucnc running ubuntu 12.04.5 LTS and linuxcnc. Bios is set to use ECP, I have tried normal and I have tried EPP, all with the same results. If I plug in the parallel after the computer starts up it doesn't switch but I can't control either axis motors


    Additional Information:
    Laser is currently not connected for safety reasons


    Additional Information:
    I am using the parallel BoB for the 40 watt C02 Laser Cutter and Engraver(blacktooth), with the supplied integrated computer running Ubuntu 12.04.5 LTS and linuxcnc. Right now, when I have the parallel header connected to the BoB(as well as usb power supplied by the computer) and I start the computer, I am able to see the first splash screen of text indicating that the computer is starting up, then the relay on the BoB switches, turning the computer off and then back on again. This happens over and over again and the computer cannot fully start into the linux os. If I unplug the parallel cable from the BoB, I can start the computer, sign in and then plug the BoB back in without it shutting down the computer. Can anyone explain why this happens? I should also say that I cannot talk to the steppers in stepconfig of linuxcnc, I get to the test this motor section and nothing happens when I try to jog either the x or y motors. In the y config, I actually triggered the relay and sent the machine back into the start up failure loop I mentioned in the beginning.

    Additional Information:
    Fixed this problem, the parallel cable was not seated well, found some screws to make a strong connection, now that part is working. Unfortunately, the stepconfig in linuxcnc is still not talking to the motor drivers and the setup for determining steps for inch in the build instructions is nothing like the set up in linuxcnc. In the instructions it says motor steps per revolution*microsteps/pulley pitch per tooth*number of teeth and in this case the recommended input would be (200*16)/.08*20 teeth = 2000 steps per inch the formula in linuxcnc is very different

    Click the link to respond:
    parallel break out board is not working-relay keeps switching my computer off when I power up

  • Where are the limit switch connections made when the switches are in series, and NC??

    One end of the limit switch circuit will be connected to the pin and NC, and the other end will be connected to COM and GND.

    For example: (the "-" is wire.)

    [Breakout board input pin] ---- ([NC on switch] [com on switch]) ---- [NC on switch] [com on switch] ---- [back to GND on the breakout board]

    An explanation of the limit switch connections is located on the brakout board datasheet: https://www.buildyourcnc.com/item/electronicsAndMotors-parallel-breakout-relay (instruction step # 1.

    Click the link to respond:
    Where are the limit switch connections made when the switches are in series, and NC??

  • What power supply do you recommend for the spindle and limit switches if I buy the USB Mach3 breakout board?

    Any of the following power supplies will be fine for powering the Mach3 USB controller:
    https://www.buildyourcnc.com/item/24v

    however, the limit switches do not need high current, so the following power supply is sufficient for the task of connecting limit switches:
    https://www.buildyourcnc.com/item/electronicsAndMotors-power-supply-24v-1a-dc

    Click the link to respond:
    What power supply do you recommend for the spindle and limit switches if I buy the USB Mach3 breakout board?

  • When wiring NC limit switches in series to the V5 BOB where are the connections made on the BOB?

    The breakout board has input pins on one side. Use these pins to connect limit switches. The return of the circuit goes to gnd which is located on the same side, where the input pins are located.

    Click the link to respond:
    When wiring NC limit switches in series to the V5 BOB where are the connections made on the BOB?

  • Do you have a wiring diagram for a 3 axis system using your compotents. It would be nice if it showed the estop, limit switches,relays...

    Depending on the Breakout board that was purchased with your electronics combo, either USB or Parallel:
    USB: https://buildyourcnc.com/item/electronicsAndMotors-electronic-component-USB-Controller-Breakout#prettyPhoto/2/
    Parallel: https://buildyourcnc.com/item/electronicsAndMotors-parallel-breakout-relay#prettyPhoto/2/

    These will have the inputs labeled on the board itself, for example:
    USB will have the inputs for all the axis from X, Y, Z, A, limit switches.
    Parallel there will be 4 inputs 10, 11, 12, 13, 16(relay). Which can be used as E-stop, Limits (for all axes if wired in a closed loop), and one relay for a spindle control on/off via mach 3 or mach 4 or a specific relay control that you desire.

    Click the link to respond:
    Do you have a wiring diagram for a 3 axis system using your compotents. It would be nice if it showed the estop, limit switches,relays...

  • Do you have a more detailed diagram of the rotary and 15A limit switches on the vlxl?

    Are you trying to determine how to wire the switches or where to place them on the Vertical Laser XL? Let me know and I will provide some pictures or video on how to do this.

    Additional Information:
    Kind of both. Have somewhat of an idea as to how to wire them but you included rotary and other limit switches. Not sure which ones to put where. Never worked with these before.

    Click the link to respond:
    Do you have a more detailed diagram of the rotary and 15A limit switches on the vlxl?

  • 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 respond:
    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?

  • should i be getting power from the parallel port? the green light is on without the usb and i think it might be causing a grounding issue.

    Yes, there is a small signal level voltage coming from the parallel port out of the computer. If the pin is high, then it will be outputting 5v and if the pin is low, it will be pulled to ground. It may appear that your parallel breakout board is powered, but will not provide sufficient voltage to properly operate the drivers. The USB power is vital for proper operation.

    Click the link to respond:
    should i be getting power from the parallel port? the green light is on without the usb and i think it might be causing a grounding issue.

  • Can you tell me what gauge wire is needed for limits switches and the spindle?

    The hookup wires you will need is 22 to 24 AWG stranded and shielded for the wiring of the limit switches and E_Stop. Our kit customers select various places for these switches, so we don't supply the wiring. If you don't use shielded cable, you will need to change the debounce setting in Mach3 (if that is the control program you are using).

    We typically use 14 AWG stranded wire for the VFD to Spindle (U, V, W) connections.

    Click the link to respond:
    Can you tell me what gauge wire is needed for limits switches and the spindle?

  • Where is the 5v terminal on the parallel breakout board to power the board?

    The parallel breakout board contains a USB port to power the board. Through the USB port, the computer delivers 5v of stable power to the parallel breakout board, but doe not provide any communication as would normally be associated with USB connectivity.

    The reason we elected to use the USB port to provide power is to remove the need for an external 5v wall adapter.

    Click the link to respond:
    Where is the 5v terminal on the parallel breakout board to power the board?

  • I am converting from a Parallel Port to the Mach3 USB. My limit switches can accomodate up to 5VDC and I want to Drive a Relay from one of the outputs. Will my switches work and do I need a 24VDC Relay?

    Yes, the best way to attach a relay to the output of the Mach3 USB board is to use an SSR (Solid State Relay) at the 24 Volt rating. This is the standard supply for this side of the Mach3 USB board.

    Click the link to respond:
    I am converting from a Parallel Port to the Mach3 USB. My limit switches can accomodate up to 5VDC and I want to Drive a Relay from one of the outputs. Will my switches work and do I need a 24VDC Relay?

  • I have a YDH-18-5 Power Supply AC Input:100-240v 47-63Hz, Ouput: 5v - 2A and need to know if its safe to use with the Parallel Breakout Board.

    The 5V power required for the breakout board can be a simple USB male to male cable, that will connect from your computer to the board itself.
    Now adding a external power supply make sure that it does not exceed a total of 5V and the standard 500 MilliAMP - 1 A.

    Click the link to respond:
    I have a YDH-18-5 Power Supply AC Input:100-240v 47-63Hz, Ouput: 5v - 2A and need to know if its safe to use with the Parallel Breakout Board.

  • I have the redleaf system for my black toe machine I have wired my limit switches in series NC after setting up in mach 3 I still get limit switch tripped after apply and ok setup can only run if I disable what am I doing wrong

    If you are using Mach3, the setting for the input pin 10 may be enabled as a default for use with the Emergency Stop. If there is no emergency stop on that pin, the reset will trip every time.

    Click the link to respond:
    I have the redleaf system for my black toe machine I have wired my limit switches in series NC after setting up in mach 3 I still get limit switch tripped after apply and ok setup can only run if I disable what am I doing wrong

  • I HAVE A 2000 WK 11–3 Z LIMIT SWITCHES GOING TO C10R10 BREAKOUT BOARD . CAN ALSO USE THEM AS MY HOME POSITION WELL. 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 respond:
    I HAVE A 2000 WK 11–3 Z LIMIT SWITCHES GOING TO C10R10 BREAKOUT BOARD . CAN ALSO USE THEM AS MY HOME POSITION WELL. NEED THE WIRING CONFIGURATION

  • Can I get a replacement computer only ? I have a blacktoe with parallel port and it seems to have stopped working.

    Sure. If you had your own computer to start with and now need a replacement for it, consider our redSprout and redLeaf systems. You can find information about them here: https://buildyourcnc.com/AssembledElectronics.aspx If you started with one of our assembled systems, and only need to replace certain components, contact our sales department at sales@buildyourcnc.com for a quote.

    Click the link to respond:
    Can I get a replacement computer only ? I have a blacktoe with parallel port and it seems to have stopped working.

  • In the video 'Primer on Homing and the Use of Limit Switches' Patrick refers to pin number "13". Is this in fact pin "i3"?

    The parallel breakout board uses pins 10 to 13 relating specifically to the pin numbers on the parallel port. It is in fact 13 and not i3.

    The mach3 USB board does use the I1-I4 using the I to represent the word "input"; hence I3 (i3).

    Thanks for the question and wanting clarification.

    Click the link to respond:
    In the video 'Primer on Homing and the Use of Limit Switches' Patrick refers to pin number "13". Is this in fact pin "i3"?