Troubleshooting Your Auto-Leveling Probe: Triggered vs Open

Are you suspicious that your Auto-Leveling Probe (Z Probe) may be malfunctioning?  Some users have seen the Z axis go upwards when they click home or when running the Auto Leveling Process (G29).  Other users have reported that the probe indicates that it is TRIGGERED constantly.

 

 

Triggered vs Open

The term "open" indicates that the end stops or probe are not closed or "TRIGGERED".  In the images below, you can see an example of each axis (X, Y, then Z) being "homed".   The M119 command is given after each axis is homed, resulting in the read-back reporting the axes being "TRIGGERED" one by one.  If your commands look like this, the end stops, probe and Printrboard are all functional.  

*NOTE: A Printrbot Play was used as the example.  If you have another model of Printrbot, your end-stop/homing positions may vary.

 

Manually home X.

HomeX.png

 

M119 = X TRIGGERED

Xtriggered2.png

 

Manually home Y.

homeY.png

 

M119 = Y TRIGGERED

Ytriggered.png

 

Manually home Z.

homeZ.png

 

M119 = TRIGGERED

Ztriggered.png

 

 

 

 

Are you seeing a different read-back than displayed above?  If your read-back constantly shows Z as "TRIGGERED",  make sure that your hot end is positioned with the tip of the nozzle at least 10mm above the print bed.  Also, check for anything metal sitting right under the probe.  If the area under your probe is clear and the Z_min shows "TRIGGERED", see the steps below.

 

Z constantly TRIGGERED? Swap connections and re-test.

Now that you have verified that X and Y end stops and connections work, Power OFF and unplug all end-stops and probe. 

  • Plug the Z probe into "Y STOP".
  • Plug your Y end-stop into "X-STOP".
  • Leave your X end-stop unplugged.
  • Manually the move X and Y out of the "home" position.

 

*NOTE: It is a good idea to label your end-stops before swapping them around. 

IMG_7491.png

 

 

Power ON, connect and hold something metal under probe.  While holding the metal object under the auto-Leveling Probe, send M119 command.  You will likely get the following read-back:

 

• x_min: open

• y_min: TRIGGERED

• z_min: open

 

 

Next manually home the Y axis (now plugged into X-STOP).  You will probably see the following read-back from M119.

 

• x_min: TRIGGERED

• y_min: TRIGGERED

• z_min: open

 

 

If your troubleshooting matches this scenario, it is likely that either your probe and/or probe extension wire need to be replaced.  It is possible for a faulty probe to still light up when metal is placed under it.  Focus on whether or not the probe communicates to the board that metal is detected - TRIGGERED/open. 

 

Click here to order a new Auto-Leveling Probe (w/ extension).

 

 

If you have followed these troubleshooting steps and the probe responds to metal by showing TRIGGERED/open when it is plugged into Y-STOP, there is likely a problem with the Printrboard.  Another sign that the Z-STOP connection is bad on the Printrboard is if the red light on the probe does not come on when metal is placed under it. 

 

Click here to order a new Printrboard Rev F6. 

 

  

 

 

 

 

 

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13 Comments

  • 0
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    Bill Mallon

    so if your setup is normal and the probe reads TRIGGERED, what do we do?

  • 0
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    Dave - PB Support Team

    Hi Bill, I apologize if I misunderstand your question, but if your setup is normal and the probe reads "TRIGGERED", that matches line 2 of the table.  To discern if either the probe or the board has an issue, swap the Y and Z end-stop connections and match your results to lines 3, 4, and 5 in the table.

    Hope that is hepful,

    Dave

  • 0
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    Bill Mallon

    Hi Dave unfortunately this does not solve my issue. As far as I can tell the sensor has simply gone bad the indicator light on top that normally only lights up when it's with 4mm of the print bed (or any metal) is on permanently and the M119 query gives a triggered result regardless of whether the probe is near any metal. I've tried plugging it into the Y stop header as well as a 5v fan header on my PC and get the same result, The light is stuck on and the sensor is apparently stuck always triggered. 

  • 0
    Avatar
    Dave - PB Support Team

    If you used swapped the probe to the Y stop header (in addition to a fan header on your computer), it sounds like you essentially matched the scenario in line 4 "Y & Z Swapped":

     

     

  • 0
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    Bill Mallon

    HI Dave, since my last message I ordered another probe and that one seemed to work initially. The printer would home Z and auto-level correctly. However a few minutes afterwards the printer began experiencing, essentially the same problem. The only difference now is the LED on top of the probe is not stuck on. The light only comes on when the probe is near metal, suggesting that it's at least partially functional. However as long as it's plugged in M119 shows the Z-Stop as triggered, regardless of whether the sensor is near anything metallic. Also if I unplug the new sensor and plug it into the Y-Stop, M119 shows the Y-Stop as triggered, indicating this newest sensor is also damaged. Is it possible the Printrboard has suffered some kind of damage where the voltage coming off the Z-Stop jumper is damaging the sensor in some way?

  • 0
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    Gfmail

    My issues have some parallels with Bill's. My Simple Metal is 2y old and has over that time worked reliably always printing while connected via USB. A few weeks ago I started having prints that inexplicably stopped in the middle. I suspected some USB issue although there have been no changes to cables or the computer. As a work-around I started printing directly from the uSD card. That worked fine for a while although I seemed to be having more extruder clogging when trying to start a 2nd print after completing one. Finally, while trying to restart after having to abort a print where the filament was no longer feeding I found I could no longer lower (home) the z-axis. The extruder will move up but never down.

    I followed the steps outlined for troubleshooting the probe. After both the normal and swapped wiring configurations, the results indicate that both the Printrbot board and the probe are bad. My questions are, before ordering both a replacement board and a replacement probe:

    1. Are there any other tests I should perform to confirm the diagnosis?

    2. What are the likely causes of this multiple failure?

    Thanks for your help,  George

     

  • 0
    Avatar
    Dave - PB Support Team

    @Bill - "Is it possible the Printrboard has suffered some kind of damage where the voltage coming off the Z-Stop jumper is damaging the sensor in some way?"

    A: I suppose anything is possible, but after speaking with our electronics guy, it doesn't sound likely that the probe is damaged.  However, I may have aided you in misdiagnosing the probe as the culprit.  If you replace the board and find that your original probe is good, please let us know by submitting a ticket for RMA and reference this forum post.

     

  • 0
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    Miguel Sanchez

    I am kind of experiencing a somehow similar problem caused after a spark jump from my finger to the printer while connected to USB (and to ground from there). 

    The probe LED responds to my approaching a metal to the bottom of it. M119 responds too, but now it says triggered whenever the LED is OFF and open whenever the LED is ON. I guess I will need to reload the firmware to get it working back to normal. 

    I hope this may help.

  • 0
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    Miguel Sanchez

    I grabed this firmware https://github.com/Printrbot/Marlin

    And changed line 258 of Configuration.h to 

    const bool Z_MIN_ENDSTOP_INVERTING = false;

    Now I am a printing happily with the same hardware (now M119 gives the right output, triggered when metal is detected and led is on, open otherwise).

    Edited by Miguel Sanchez
  • 0
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    Dave - PB Support Team

    Thanks Miguel!

  • 0
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    Miguel Sanchez

    Hi Dave,

     

    Joy was only temporary :-(

    After printing a couple of parts, today I have found the probe does not work anymore.

    While LED is still working, the output signal only swings from 0.5v to 0.15v. So probe needs replacement.

    z_min is no longer working either, stating open all the time no matter the input voltage (in fact it is stuck at GND). So board needs replacement too. 

    I reckon I just happen to experience a transient failure mode between the ok and no go mode that explains why the input was seen as inverted for two days. 

    My impression is that once z-min input became stuck at GND it took the life of the probe's output transistor.

  • 0
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    Thomas Briggs

    In a normal configuration, my z_min always shows "TRIGGERED" while X and Y function normally when manually triggered. After swapping Z and Y connectors, Y always shows "TRIGGERED" and manually triggering the Y axis (connected to Z connector), z_min always shows "open". Is it just my Z Probe that failed or is there something wrong with the board as well?

  • 0
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    Dave - PB Support Team

    This guide has been updated (3/6/17).  So, references to "the table" are no longer relevant.  Thanks for all of the discussion everyone.

     

    Dave -pb

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