Is anyone else using E1P1 / E1P0 to switch output #1 ?

[Tweakie.CNC]

I am having an issue with switching output #1 with the commands E1P1 and E1P0.

For most of a program it works just fine then suddenly gets confused (particularly with short moves) then returns to working just fine again.
Despite much experimentation I have not been able to get to the bottom of this or find the cure.

If anyone has experienced this problem and discovered the reason or found a cure I would be most grateful to learn the answer.

I have attached a simple GCode which exhibits this problem.

Thanks,

Tweakie.

[Hood]

Just curious the reason you are using this? If its for no delay operation of turning on/off your laser I wonder if M10/M11 would work better?
Hood

[Tweakie.CNC]

Hi Hood,

Thanks for your response - Yes it is for no delay, or switching at the point of the axis movement, for a laser.

Funny enough the M10 /M11 combo also suffer similar, although slightly different, behavior. There is definitely something strange here as I have tried different computers with the same result.

I have attached a modified (m10/m11) version of the earlier GCode just in case anyone wants to see the difference.

Tweakie

[stirling]

Hi Tweakie - don't know if this is any use to you but a while back I spent a bit of time looking at reducing the delay after switching outputs. http://www.machsupport.com/forum/index.php/topic,13206.msg86699.html#msg86699 (post #11)

Cheers

Ian

[Tweakie.CNC]

Hi Ian,

Thank you for the link, which I had not seen before. I have just given this a try (got quite excited) and although it may speed the Output # ? switching time there is still a delay before the next line of code is executed when using M3 or M1001.
With cutting acrylic this delay is unimportant to me it is just with engraving where the depth varies at the start and end of the kerf.
It is so annoying that the E1P1/E1P0 works so well... 'when it works'.   

Tweakie.

[stirling]

although it may speed the Output # ? switching time there is still a delay before the next line of code is executed when using M3 or M1001.

Hi Tweakie - The timings I've given in the thread (via scope) were between the edge of the ouput going active and the edge of the first step pulse on the next line that commanded movement. i.e. NOT the time it took the output to go active. Worked every time for me and like I say I got it down to ~ 0.05 seconds, but looks like one of those one's that don't work for everyone for whatever reason.

Cheers

Ian

[Tweakie.CNC]

Hi Ian,

Thanks for the info, I must look into this a bit more then. I didn't actually measure anything, just looked at the results in a piece of scrap perspex.
Just out of curiosity and assuming you have a better memory than me, what acceleration figure were you using for your X -Y axis ?.

Tweakie.

[stirling]

5000mm/sec^2 (velocity 15000mm/min)

[stirling]

fingers too fast for brain - why does that make any difference?

Ian

[Tweakie.CNC]

Hi Ian,

fingers too fast for brain - why does that make any difference?

The faster an axis takes off from a standing start and the quicker it stops the less drawn out the unwanted increase in depth of cut at the start and finish of the kerf becomes. (on wood this is shown as a dot at each end of a line - quick acceleration, small dot - slow acceleration, bigger dot).

5000mm/sec^2 (velocity 15000mm/min)

You must have super low mass in your axis to achieve that Velocity and acceleration. My poor little steppers might just about manage a squeak. 

Tweakie.