EMC bug? axis position values instantly change after end of program

[davidma]

I'm using EMC 1.0-30 (at least that is the debian pkg version), based on BDI-4.30 I think. I downloaded the sources and rebuilt the modules so it would work with my new Xylotex (i didn't feel like firing up the soldering iron and making a cable or breakout this evening).

It works fine, just one problem: at the end of a program after the last instruction, the indicated positions on one or more axes will instantly change to some other value, although nothing actually moves. I think I've ruled out missed steps since the positions is just fine until the end of the program, after the last movement, it gets its position fouled up. This makes it kind of inconvenient to run a program multiple times!

Does this have something to do with the home switches? My old home brew driver had the home pins wired closed (i forget if they are active high or low). The xylotex, I think, doesn't do anything with them. I haven't cracked open the xylotex yet because it is new, has a sticker on it to detect if its opened, and I want to let it break in before cracking it open and possibly voiding the warranty.

I never had this problem with the old homebrew board.

I'm trying to avoid having to do a full OS upgrade, I'm aware there are probably much newer versions out.

[cyclestart]

Originally Posted by davidma I'm using EMC 1.0-30 (at least that is the debian pkg version), based on BDI-4.30 I think. I downloaded the sources and rebuilt the modules so it would work with my new Xylotex (i didn't feel like firing up the soldering iron and making a cable or breakout this evening).

I'm curious why you've gone through this effort. Maybe ubuntu isn't you're cup of tea? I have Xylotex and getting it running was as simple as choosing the pinout with a recent linuxcnc.org release. Ah, (as the cofee starts kicking in), Xylotex didn't provide a cable?
edit/ Oops, the xylotex pinout is a relatively recent emc addition /edit

It works fine, just one problem: at the end of a program after the last instruction, the indicated positions on one or more axes will instantly change to some other value, although nothing actually moves. I think I've ruled out missed steps since the positions is just fine until the end of the program, after the last movement, it gets its position fouled up. This makes it kind of inconvenient to run a program multiple times!

Does the problem persist following this advice?
http://www.mail-archive.com/emc-user.../msg03400.html

Homing can be done without home switches. Are you using G92 by any chance. I'm willing to play along at home if you post some code

I haven't cracked open the xylotex yet because it is new, has a sticker on it to detect if its opened, and I want to let it break in before cracking it open and possibly voiding the warranty.

Not sure what Xylotex's view is on this. If the board and case is anything like mine there really is no option but to open the case if you want to use the home switch example on the xylotex website.

I'm trying to avoid having to do a full OS upgrade, I'm aware there are probably much newer versions out.

Ok, my first question is answered! Emc keeps adding useful features and I encourage you to make the move. It's worth the effort imo.

[acondit]

David,

Even if there is a bug in that system, I would be surprised if anyone would be willing to go back and figure out the code to fix it. We are on emc2 version 2.2.1 and that is a lot of water under the bridge. I am with Cyclestart, bite the bullet and upgrade to the current version.

Alan

[davidma]

Thanks for the tips. I'm downloading the latest BDI ISOs and also the Ubuntu EMC Live CD. I'll give it a try, and assuming no problems, I'll upgrade. I've got enough spare PCs lying around here I can try it first on another.

What are the pros and cons of BDI and the ubuntu LiveCD? I am pretty up-to-speed on Debian but have not used Ubuntu yet, although I believe it is derived from debian, right? While searching for tips on-line I gathered there was some kind of a split with the BDI maintainers over GPL terms and access to CVS repositories, so maybe that's why there's a forked project?

I'm happy with the xylotex. Sure, I probably could have put together something with equivalent speed on my own, after 6 months of spending weekends messing around with breadboards, ordering parts from different suppliers, making PC boards, etc. I decided it was easier to just shell out. The motors were a bolt-on replacement (I already had NEMA23 pac-sci steppers). I got the 4-axis and I have a rotary table that I will make a stepper mount for next.

[acondit]

Originally Posted by davidma Thanks for the tips. I'm downloading the latest BDI ISOs and also the Ubuntu EMC Live CD. I'll give it a try, and assuming no problems, I'll upgrade. I've got enough spare PCs lying around here I can try it first on another.

I believe that BDI is the old version of emc. The ubuntu live cd should be the emc2-2.2.1.

What are the pros and cons of BDI and the ubuntu LiveCD? I am pretty up-to-speed on Debian but have not used Ubuntu yet, although I believe it is derived from debian, right? While searching for tips on-line I gathered there was some kind of a split with the BDI maintainers over GPL terms and access to CVS repositories, so maybe that's why there's a forked project?

I believe that Ubuntu is debian derived or vis versa. Someone said something about Ubuntu being the bleeding edge and Debian being more stable but I really don't know for sure.

Original EMC was public domain and some people have used it to create proprietary projects. EMC2 is GPL'd. A bunch of the developers were not happy with the idea of someone taking their work for incorporation in proprietary projects and not releasing the source for the modifications. And there were some problems with SourceForge's servers for a while. Complicated I guess.

I'm happy with the xylotex. Sure, I probably could have put together something with equivalent speed on my own, after 6 months of spending weekends messing around with breadboards, ordering parts from different suppliers, making PC boards, etc. I decided it was easier to just shell out. The motors were a bolt-on replacement (I already had NEMA23 pac-sci steppers). I got the 4-axis and I have a rotary table that I will make a stepper mount for next.

EMC2 has ini files for xylotex.

Alan

[davidma]

I tried out the ubuntu live CD and I'm very happy with it. I was able to get it working fine of the live CD, so I went ahead and blew away the old BDI install and I'm installing the live CD to the HD now. I see no reason to keep the old version around.

The new UI is great of course, and that bug/behavior that started this thread is not present in EMC2. It's like I've been living in a cave the past couple years with old EMC, weak/slow steppers and a wimpy homebrew board that could only do like 1 A/phase.