M558 Axxx ?



  • Hello, try to have three sounding point polls.
    I put this command : M558 P1 C"zprobe.in" H5 F120 A03 T10000 S0.03 , but I only get two polls at most each time. Thank's



  • @Rudy2A From the documentation (https://duet3d.dozuki.com/Wiki/Gcode#Section_M558_Set_Z_probe_type) :

    The A and S parameters control multiple probing. Probing is repeated until two consecutive probe attempts produce results that differ by no more than the S parameter; then the average of those two results is used. However, if the number of attempts specified by the A parameter is reached without getting two consecutive results within tolerance of each other, no further probe attempts are made and the average result of all the attempts is used.

    So if your first two probe values are within your S parameter (0.03mm) of each other, it will only probe twice and take the average of those two. If instead, they are more than 0.03mm apart, it will probe again a third time (as you're seeing). It will then either take the average of the final two (if they are within 0.03mm), or the average of all three probes (if not).

    You can decrease your S parameter to make sure they are more consistent (and so more likelly to probe more times if not). Personally, I have a Piezo which is pretty accurate. I have S0.01 and A5, but typically only see it probing twice, maybe sometimes three times.

    Also, I think it should be A3 not A03, but that might not matter...


  • Moderator

    If you're going to use an A value I suggest you use at least 5 or more unless you have a very consistent probe. Normally you should get 2 in a row at least, but on the random times when it's a bit off it will retry until it reaches the value of A until at least two consecutive results match within the S value. This can mean that with a small A value you could flunk out on probing and it will error.



  • Thank you for your explanations !


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