Limit Switch problems on RAMPS 1.4 and custom built 3D Printer running Marlin 1.1.0-rc6

Question

So I am trying to fix a custom built 3D printer for my institute and am running into a problem I can't wrap my head around.

So the limit switches for Y-axis and Z-Axis work just fine, but the X-Axis does not.

All three switches are Makerbot (3-pin), and all three light up the LED when they get pressed. However the X-axis does not get recognized by Marlin. When I diagnose with M119 command it does not show as triggered even though the LED is on. All the other ones do.

All three switches are connected to min (X-min, Y-min, and Z-min).

Could this be a firmware problem? Or perhaps my RAMPS 1.4 has burned out the X-axis signaling? (I doubt this because the LED on the switch still turns on).

Let me know if you need any more info to diagnose the problem.

P.S. I have also replaced the X-Axis limit switch with a brand new one and the same result happens: LED turns on upon activation but it doesn't get recognized by the machine.

Pᴀᴜʟsᴛᴇʀ2 · Answer

Considering you're having issues with the board, and the limit switches appear to be registering, but the board isn't doing anything about it, a first good step would be to update the firmware to 1.1.9 as @0scar states. If the update in the firmware doesn't do the trick, then move on to doing as he suggests with changing the Xmax/min stuff around. This just seems like a good first logical step to getting it fixed.

Answered by Pᴀᴜʟsᴛᴇʀ2 on November 20, 2021

0scar · Answer

To rule out problem with the switches itself, you can change the Z-min and swap it with the Y- or Z-min. Once you found out that you get the same issues you know that your X endstop module is working (unless they both are faulty, but the odds are small for that), but the signal change is not registered by the board. This could be a faulty port/pin of the X-min port / attached microprocessor pin. What you could do to try to diagnose that is using the X-max header on the board. In order to use that header for X-min, you need to change some code in pins_RAMPS.h, change:

//
// Limit Switches
//
#define X_MIN_PIN           3
#ifndef X_MAX_PIN
  #define X_MAX_PIN         2
#endif

to:

//
// Limit Switches
//
#define X_MIN_PIN           2
#ifndef X_MAX_PIN
  #define X_MAX_PIN         3
#endif

Recompile and upload. Please use the latest sources, 1.1.9, 1.1.0 is very old.

//
// Limit Switches
//
#define X_MIN_PIN           3
#ifndef X_MAX_PIN
  #define X_MAX_PIN         2
#endif

to:

//
// Limit Switches
//
#define X_MIN_PIN           2
#ifndef X_MAX_PIN
  #define X_MAX_PIN         3
#endif

Recompile and upload. Please use the latest sources, 1.1.9, 1.1.0 is very old.

Limit Switch problems on RAMPS 1.4 and custom built 3D Printer running Marlin 1.1.0-rc6

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