SN04 -N NPN Sensor for Z Axis

  • Has anyone used this on the Duet Wifi? A search turned up nothing.

    This came with my Tevo Tarantula and it worked fine as a bed sensor for the Z Axis on the MKS Base V1.3 board.

    In looking at the options for setting up the Z probe, I think it should probably work on the DuetWifi, but I have no idea if I have to rearrange the wiring on it in the plug that connects to the board, or which settings I should be using to configure it properly.

    I plugged it into the Z endstop connector and it does nothing.

    I'm afraid my electronics knowledge is limited.

    Would someone be able to point me in the right direction to figure out what I need to understand to get this configured?

    Tim Vukman

  • How about a link to the sensor?

  • administrators

  • Hi number40fan
    here is a link to the datasheet

    Hi T3P3Tony
    I have read through that section several times now. It is now my second day with the Duet Wifi, so my knowledge of how it does things and what signals it looks for is now higher than nil. Not much higher, but I have control of the motors and the x and y limit switches are working. Z does not work with a standard pressure switch like x and y have. It lights up on the board, so I know the switch is physically being closed. I have the settings the same way as x and y I think. I put a meter on them and they start off high and get pulled low when tripped.

    Since my SN04-n probe is still attached to the hot end, I plugged it in. As stated, it does nothing. I am not going to pretend to understand what is written in the Wiki. Over my head, especially using pins from E1.

    There are three wires on the cable for it. Brown, Blue and Black. Brown comes out on Pin 1 (with the little guide bars on the connector facing toward you), Blue comes out on Pin2 or the center pin, and Black comes out on Pin3 or the right side.

    I was really hoping that someone had one working, and they could tell me if I had to move any of the wires around on the connector, and if it would then plug in to the Z end stop pins on the board.

    If there is another sensor that is plug and play, I would be happy to order one. I'd rather not get into soldering wires and diodes on the new Duet Board.

  • OK

    I did some digging on the SN04-N. Now I understand why E1 is an option. This is a 12V ~ 30V device. It is also digital. I should therefore be able to set E1 for high or low (whichever way the sensor goes).

    I think Mode 6 would be the appropriate choice.

    I shall dig deeper

  • It looks like you will need a diode to begin with. Get that first and we can go from there.

  • administrators

    Re your comment 'Z does not work with a standard pressure switch' see #1 at

  • Hi number40fan
    I appreciate the input and you time to assist. I am reluctant to engage in anything that will involve soldering on the DuetWifi. I need a solution that I can add to the hot end and wire up to the board without modifications.

  • The diode would be added to the wiring of the sensor. Nothing needed with the Duet other than some settings in the config.g.

  • Hi dc42
    Thank you for the link that you have provided. What I was referring to when I said it didn't work was that it is not working as an end stop at the moment. I hope to figure out why today.

    Surely there is a probe that people are using to sense the bed reliably, and one that does not require modifications to the DuetWifi board.

    I have ruled out using the SN04-N as it seems it will require modifications to the DuetWifi.

    I would appreciate a recommendation on such a probe, and one that will work with a glass surface over the bed.

  • DC42's IR Probe sounds like the ticket then. Plug and play.

  • Forum user DJDemon sells a piezo based sensor that is basically plug and play if you have a E3DV6 Hotend:

    I use it on one of my printers and I'm very happy with it…

    IR probe is also nice but you must paint the glass black to get consistent results

  • Thankyou number40fan and whosrdaddy

    I chose the IR Probe as it appeared to be the easiest setup on my hot end.

    Best regards,


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