M669 S and T values

cjm

I have a few questions regarding the M669 S and T parameters which I’d be grateful for any help with:

What are the minimum allowable values for the S and T parameters?
If I set S0.1 does this mean I can be confident my CNC will pause within 0.1 seconds?
Similarly, if I set T0.1, does this mean the CNC will pause within 0.1mm?

droftarts

@cjm Try setting them very low, ie 0.0001, then send M669 to show what settings are being used. I don't have access to any Duet board to try it at the moment. Otherwise @dc42 will need to answer.

Ian

cjm

@droftarts Thanks, Ian. Will have a go this weekend…

cjm

@droftarts It appears that M669 doesn’t report the S and T values? This is my console output:

26/11/2021, 21:11:46: Connected to 192.168.0.9
26/11/2021, 21:12:19: M669 S0.001
26/11/2021, 21:12:32: M669: Kinematics is Cartesian, matrix:
1.00 0 0
0 1.00 0
0 0 1.00
26/11/2021, 21:12:46: M669 S1.0
26/11/2021, 21:12:52: M669: Kinematics is Cartesian, matrix:
1.00 0 0
0 1.00 0
0 0 1.00
26/11/2021, 21:14:17: M669 S1.0 T1.0
26/11/2021, 21:14:27: M669: Kinematics is Cartesian, matrix:
1.00 0 0
0 1.00 0
0 0 1.00

jay_s_uk

@cjm that's correct. I've already raised this

dc42

@jay_s_uk the latest builds do report the S and T values, but the latest released beta doesn't.

cjm

@dc42 Thanks for clarifying the M669 reporting of S and T.

There has been some discussion of setting S and T to small values, so that the time delay and distance moved after a pause command can be reduced.

I wondered whether you be able to explain a little more about any trade offs as S and T are reduced ?