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LinuxCNC controls CNC machines. It can drive milling machines, lathes, 3d printers, laser cutters, plasma cutters, robot arms, hexapods, and more.
http://linuxcnc.org/
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motion.feed-upm not as documented #1438

Open phillc54 opened 2 years ago

phillc54 commented 2 years ago

The motion man page states that motion.feed_upm is in machine units per minute.

The actual reported value is G-Code file units per minute. e.g. a metric machine running a G20 file, feed-upm reports inches per minute rather than mm per minute.

I can change the documents if necessary but I am reporting this in the hope that the documentation is correct and the reported value can be changed.

andypugh commented 2 years ago

I wonder if anyone is depending on the current behaviour?

phillc54 commented 2 years ago

Knowing my luck there would be. :)

andypugh commented 2 years ago

Maybe the answer is to create yet another pin, motion.feed_mupm ? (or something else, of your choice)

SebKuzminsky commented 2 years ago

Pins are very cheap in LinuxCNC. I suggest creating two new pins, motion.feed_inches_per_minute and motion.feed_mm_per_minute, and updating the documentation to correctly describe the current behavior of motion.feed_upm.

This provides full backwards compatibiliy and maximum flexibility for people who want to know the feed in either of the standard units.

rodw-au commented 2 years ago

Because pins are cheap, I think the units should be per second in line with all of the other velocities reported. With motion.feed_upm, its not possible to easily compare feed rate with current velocity in halscope which I have found very frustrating. Either add these pins or use them instead of Seb's suggestions.

motion.feed_inches_per_second
motion.feed_inches_per_second
SebKuzminsky commented 2 years ago

How about four new pins:

We should probably keep motion.feed-upm unchanged for now, but note in the docs the behavior that @phillc54 reported. The current manpage is self-contradictory, claiming both that motion.feed-upm is in machine units, and that it's based on the program's F-word (which changes units with G20/G21).