How does the dual limit Z access work?

I have a LR3 that I’m getting close to finishing. Can someone tell me what I should see when I select the Z home on the firmware screen? I have a SKR Pro 2.1 with the stock firmware that was pre loaded. In my case, the gantry moves up and when it hits the end stops, One of the stepper motors stops but the other motor keeps moving even though the end stop for that motor has also been triggered. I can provide a small clip if it’s allowed to upload if needed. Actually, I’m starting to question if the firmware that came preloaded is correct. For the CNC would I have an icon for filament unload?

Ok so I guess pre loaded is not loaded? I downloaded new firmware.

Not actually sure if its the correct firmware due to the machine name not saying anything about LR3. The file name was V1CNC_SkrPro_DualLR_2209-2.1.1 however.

After the new firmware, I can raise and lower the gantry with no issues. However when I home, only one stepper spins while the other just sits. Perhaps a setting somewhere? Any suggestions?

The 515DL marks that firmware as version 515 dual end stop Low Rider. The same firmware for the LR2 and LR3 works, so you definitely have the correct firmware for a LowRider3.

The stop switches should be wired in normally closed mode. These are (usually) the 2 outside edge pins on the switch. The center pin is not used. It does not actually matter which one is ground and which is signal. On the main board, they should be connected to the signal and ground pins. The +5V pins are not used.

The TFT is still very much aimed at 3D printing, and so it will look like it is configured for 3D printing, with functions that are aimed at it as well (like filament unload) we can safely ignore that. There have been CNC specific builds for the TFT, but they do not work on the GD processor version of the TFT which you have. The firmware that you have for the TFT seems correct.

You may have your end stop switches incorrectly or incompletely connected.

This is from memory, please check docs.

There are 7 motor connections on the SKR Pro 1.2. From the power connectors they are X, Y, Z, Z, E0, E1, E2. They should be connected as follows:

  • X → X motor
  • Y → Y1 motor
  • Z → Z1 motor
  • Z2 → left with jumpers over the pins
  • E0 → Y2 motor
  • E1 → Z2 motor.

End stops are labelled as X, Y, Z, E0, E1, E2.

  • X → X end stop switch on the core
  • Y → Y1 end stop. This must be the same side as the Y1 motor on the Y motor connector
  • Z → touch plate probe
  • E0 → Z2 end stop. This is the same side as the Z2 motor on the E1 motor connector
  • E1 → Y2 end stop. This muist be the same as the Y2 motor connected to the E0 motor connector
  • E2 → Z1 end stop. This is the same side as the Z1 motor connected to the Z motor connector

Some of this sounds a bit weird, but it’s because Marlin treats the X Y and Z all as minimum side stops, so the Z stop cannot be used for a maximum limit switch. Though the other switches are labelled as E0, E1, E2, they are treated as X Max, Y Max, and Z Max.

If you do not have a switch connected (Or if you have the touch plate connected to the Z stop connector) then the stop will read as “triggered” and the motor will not move during homing. It may move about 5mm or so in the wrong direction after the other switch is triggered.

Edit: Use the command “M119” to check the status of your end stops.

Sorry for the late reply. I’ve been working on the table that will support this project. Thank you for the helpful information. In my case, it looks like one of the end stop connectors came off of the SKR Pro. It was probably my impatience that wanted to try everything out before the SKR was properly mounted in something. No really the best fit with the connectors to the SKR. Is there a name or part number to change out the connector for a better fit?

I believe the SKR connectors are JST-XH connectors pretty sure I used these…

If the connector comes off of the board, the stop switch will read as triggered.

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I can confirm jst xh for end stops

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