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G04 dwell command maximum value


I’d like to use the G04 dwell command as a timer on the order of 12-24 hours. I understand this is not it’s intended purpose and as such may not work. In fact, a G04 P54000 command only dwelled for 1579 seconds as opposed to 54000. Am I running into register overflow situation or something? Is the maximum dwell value a function of the particular control? I did this test on an OpenBuilds Black Box Controller. I have yet to try it on my X-Carve controller.


G04 P54000 would be 54,000 milliseconds OR 54 seconds.
Add a “.” or “.0” after the value and it will change it over to Seconds, so the command would be:
G04 P54000. Or G04 P54000.0

Alternatively you could use X inplace of P and the value is seconds by default without the addition of the period. Would work like this:
G04 X54000

The Max time is 99999.999 seconds (using a full seconds command; like the Period or the X function)

Can I ask why?

I don’t think so, but I think there is a maximum time limited by the Grbl config. Increasing it would have a negative affect on responsiveness.
Code source: grbl/config.h at bfb67f0c7963fe3ce4aaf8a97f9009ea5a8db36e · gnea/grbl · GitHub

Hmmm…is that repeatable?

The P always represents seconds.
@SethCNC You may have been doing research on non-Grbl based machines?

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That’s quite possible

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