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

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limit and home switch

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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 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.

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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

Make sure to wire the limit as normally open.

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[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?

You can use any of the inputs on the mach3 controller. If there is a free terminal input terminal, use that one. You will need to modify the input number in the inputs tab in config->Ports&pins to assign the limit to the correct input number. When adding the pin number, make sure that the port number is 3.

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Mach 3 USB motion card: what two pins do I use for the limit switches and E stop button? One of the wires pulled lose and I don't remember what the other contact was.

All USB boards, are tested and checked before shipment for all axis, and inputs. Here is a link with clear instructions on how to setup Planet-CNC (http://www.planet-cnc.com/faq/machine_setup/).

Please check continuity and for any crossover disruption when wiring your board, try to wire each as cleanly and with out crossing any live power wires and or motor motion wires.

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I have a usb cnc driver board on your 1'x3' cnc and i cant get the z+ limit switch to stop the machine in the provided software. It registers the button but doesn't inhibit movement. inversly the button works when selected as '-' for negative movement.

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

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limit and home switch

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Using Mach3 and the USB Controller, In initializing the 'Ref All Home' the machine goes thru the procedure of zeroing out 'Z' than move to zero out 'y', but when it move to 'x' it just stops when it hits the switch instead of zeroing out?

We have a tutorial on setting up limit switches here(

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Diagnostics(Alt7) page-LED (4th from left on top row) is on. Having trouble configuring Limit & Home Switches. I think this LED is for pin 15. Any ideas where to look to diagnose?

If the computer has been tested to be functional, it is most likely the breakout board which is faulty. Replace the breakout board and it should solve these issues.

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My blackfoot 4x8 Starts sending erratic commands to the machine randomly in the middle of a program or freezes altogether. Replaced USB Cable, updated software, updated firmware, tried other computers. What else should I do?

You will definitely want to adjust your debounce setting in mach3 if your emergency or limit switch is engaging.

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Did you ever fix this issue? I am having the same problem.

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Did you ever fix this issue? I am having the same problem.

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Did you ever fix this issue? I am having the same problem.

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Did you ever fix this issue? I am having the same problem.

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Did you ever fix this issue? I am having the same problem.

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Did you ever fix this issue? I am having the same problem.

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Did you ever fix this issue? I am having the same problem.

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Did you ever fix this issue? I am having the same problem.

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Did you try changing the denounce setting?

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Meant to say denounce.

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When I start my spindle I get a emergency stop in Mach 3. I have run shielded cable and it is grounded at the VFD it is wired per you site instructions. any idea what to check

Absolutely! You can have almost unlimited limit switches and home switches on this controller. It all comes down to the wiring scheme used. I recommend the home switches be on separate input terminals. For example, IN1 would have the X home switch, IN2 would have the Y home switch and, IN3 would have the Z home switch if you plan on using home switches for the Z axis.

Adding the limit switches, these can be located on any input you want, even on the IN1, 2 or 3. The wiring scheme I like to use is as follows:
- IN1 has the X home, X limit ++, and X Limit --
- IN1 has the Y home, Y limit ++, and Y Limit --
- IN1 has the Z home, Z limit ++, and Z Limit --

In most cases, the Limit -- is the same switch as the Home switch.

These can be wired as NC (Normally closed) as a serial scheme, or as NO (Normally open) as a parallel scheme.

To understand the limits and wiring schemes, check out this video:

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[575] Hi, for the manage the limit switches, is it possible to have, for example, the same limit switch for X-- and X homing? And what is the configuration in mach3? In my CNC machine they are in the same position. Thank you

A 24V connection to the USB motion card is only needed if you are using limit switches (inputs), powering the spindle/VFD speed and direction, and for the outputs, for powering other devices (mist, coolant, etc.).

If you are using a VFD (Variable Frequency Drive, also called Inverter) for a spindle, they typically have a 24V out terminal that can be used with our USB motion card. If you are not using a spindle/VFD (we highly recommend one), then you will need to purchase a 24v power supply to power that side of the board.

The outputs mentioned above are to connect to external devices and will require a relay (a mechanical switch that is controlled by a digital signal). This mechanical switch can turn on a device like coolant and mist, or even a router, if you are using one. A relay is required to turn on these devices because the devices are typically higher voltage, like mains (110v or 220v). So, a relay can turn on or off a high voltage device with a lower voltage (24v) signal.

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What would be your recommendation for "power supply 2 (24vdc)" connecting to USB motion card? Are there any videos explaining it's connection to the relay coil? (not quite sure what relay coil is)

If your axis shutters and will not move unless moved by another force, that sounds like your acceleration is set too high. Lower the acceleration until it works well, then lower it a bit more to have a margin of safety.

IF that didn't work, try swapping the X and Y drivers. That way you will pinpoint if the issue is the driver. If the proplem persists, then there may be an issue with the motor itself.

The X and Y drivers can be easily swapped by swapping only the motor wires.

- Remove the x-axis motor wires from the X driver.
- Remove the Y motor wires from the Y driver.
- Insert the X motor wires into the Y driver.
- Insert the Y motor wires into the X driver.

Now the Y-axis will move the gantry. Test the Gantry movement by moving the Y axis using the up and down arrow keys (mach3).

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X AXIS STEPPER MOTOR STALLS AND SHUTTERS WHEN COMING FROM A STAND STILL WON'T MOVE WITHOUT PUSH BY HAND. I TOOK THE CHAINS OFF SPUN FINE WITH OUT LOAD. HAVE CHAIN HOOKED UP CAN MACHINE BACK FORTH HAND, NO HANG UPS OR ANYTHING, BUT TRY TO IT DOESN'T JUST SPINS OUT. ANY SUGGESTIONS?

I created a video that demonstrates the wiring and Mach3 configuration for the Mach3 USB controller. It is the last video on the following webpage:
https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach3-USB-Board

If you have a different controller, let me know and I can provide further inforatmion.

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Hello, After watching the tutorial to set up my spindle in Mach3, My outputs are not working. Any help would be appreciated. Just Simple on/off.

The Mach3 USB interface card uses 5V (powered from the computer's USB) and a 24v to power the inputs, outputs and spindle control

the mach3 usb interface can be found here:

https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach3-USB-Board

But the mach3 usb does not absolutely need the 24V supply. The 24v supply is only needed if you will be using limit switches (I1-4), VFD controlled automatically and for use with the outputs (O1-4)


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The 36v 8.8 amp power supply we typically recommend is for powering the stepper motor drivers.

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The electronics for my current cnc machine has a 36v 8.8 amp power supply. Is this power supply sufficient to power my new Mach3 USB interface?

Most likely, the driver is not receiving the high or low signal for the direction terminals. The way direction works for an axis is the controller will output a high signal (5V) for one direction and low signal (0V) for the opposite direction. If the signal is always at one signal, say 5V, whether it is commanded in one direction or the other, then the axis will only move in that direction.

To solve this problem, make sure that the wiring is secure at both ends (from the controller to the driver). Also, make sure the Dir+ and DIR- are both wired correctly (i.e. the Dir- is connected to the signal gnd on the controller and the ZD is connected to Dir+ on the driver.

You can use a multimeter to determine the voltage at the ZD terminal by:
- setting the multimeter to DC voltage (the V with a straight line, or dashed line above the V)
- place the black lead on the gnd terminal
- place the red lead on the ZD terminal
- press the page up button and check the voltage
- press the page down button and check the voltage.

You should see the voltage change from 0V to 5V or vice versa.

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Hi I have just set up my machine using a mach 3 USB board I can only get the Z to go in one direction Y and X are Ok I have check wiring and looked at video over and over what have I missed??

The diagram for wiring the USB interface board is located here: https://buildyourcnc.com/item/electronicsAndMotors-electronic-component-USB-Controller-Breakout#prettyPhoto/2/

Under the board illustration, there are three smaller diagrams of limit switch wiring. On each, there are two connections, the GND and the pin which are labeled at the ends of the circuit on the diagrams. The pin side would go to the axis label ++ or -- terminal (i.e. X++, or X--). The other end, labeled GND would connect to any ground terminal on the board.

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I am using 5 limit switches on my 3 axis machine. I am using the usb controller for planet cnc. I would like to know where all the wires related to the limit switches get connected? A diagram would be helpful.

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.

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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

(These steps are to be taken with precaution, due to the fact that we do not know the model or manufacturers specifications for your BoB)

Here is a link to our CNC electronic videos(

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I have a CNC Machine from China, and the Breakout Board is not Labeled. Is there any way to test the board using Mach3 to find out the pin designations? db25 bob

If an axis is showing play when there is force against the axis (force in the opposite direction imposed on the bit when cutting material), the problem may be in the mechanical system. If the mechanical system is roller chain and sprocket, or rack and pinion, check the sprocket or pinion gear to confirm the tightness of the set screw. If the mechanical system is a lead screw, confirm that the coupling is secured well to the lead screw and the motor shaft.

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Every time the machine starts to cut a new pass it jumps +.033 inch on the x axis. Does anyone have any idea why it might do this?