Output voltage on LPT port varies with OS on laptop?

[Beezer]

I have come across a puzzling issue with the Toshiba laptop I use for my CNC router and wonder if any of the computer experts on the Zone have a possible cause and solution.

My laptop is a Celeron 400 and until recently I had Win98SE running on it.
I had no problems with it controlling my CNC router with Win98 and was even able to control the Opto-Relays I use to turn on the Router motor and the vaccum. These relays require min. 3VDC to activate.
Now I just recently reformated the laptop to so I could install Win2000 on it, which I need to run the newer version of CNC control software I want to use but now I can no longer activate the Opto-Relays. I checked the voltage coming out of the proper pins on the parallel port and it read 4.1VDC but once I connect the parallel cable to the control box on my router, the voltage
reads 1.9VDC under load. All I can figure is that I am not getting the same amount of voltage & current out of the parallel port now under Win2000 then I did under Win98.

Does this make sense to anyone?

I didn't think an operating system could have that kind of control over a computers output voltages.

Thanks,

Carl

[CNCadmin]

Yup, I think I have the same problem, and I think what you're saying makes sense.

[Beezer]

I am going to reformat the computer again and put Win98se back to see what happens.

I will post my findings. This should be interesting.

[pminmo]

I suspect the laptop parallel port can be setup in one of three different compatability modes. The different OS's set them up differently.

http://www.lvr.com/parport.htm

Get into some of the details of the setups and differences, It's a really good site for reference.

Phil

[Beezer]

Well I got Win98 re-installed on the laptop but that still didn't help. I was able to move the steppers but could not get the Opto-relays to trigger. I decided to hook up the router to a desktop computer, which was running XP, and I was finally able to get the Opto's to work. The strange thing is that I checked the voltage coming from the parallel port on the desktop and it was reading 3.8VDC but I am reading 4.2VDC on the laptop. Not sure what changed in the laptop since I first put Win2000 on but it seems like I am not getting enough Amps to go along with the voltage on the parallel port. Maybe I damaged something in the laptop somehow.
Going to keep trying different variations but I guess I will just have to wait till a get another desktop computer for my router.

BTW... When I looked in the "hardware settings", both in Win2000 and now with Win98, it says it is a "ECP LPT" port installed. I could have sworn that it said "EPP LPT" the first time under 98 before I put 2000 on for the first time.
In the Bios it says it is a "ECP" though. It is really strange that everything was working fine before I reformated the first time. Oh well.

[arvidb]

It's usually possible to set the compatibility mode of the port in the BIOS setup. You could probably change it to EPP.

Windows will install drivers that fits the type of port set in the BIOS.

Arvid

[Beezer]

I tried that but it's not giving me the option of EPP in the Bios. Only ECP. I am going to try and put the original OS on that came with the computer which was Win98 (not SE), then go from there. Once I get a desktop for it my problems with be solved. ( I hope. )

[Beezer]

I finally was able to get my laptop to activate my opto-relays like it did before I first installed Win2000. It seems it definately had something to do with how the operating system managed power to the parallel port. I reformated yet again and installed the original operating system (Win98) that came with the Toshiba laptop when I first got it. It seems the version of Win98 that comes with the laptop has a few differences with it over the standard, off the shelf version. It seems to have some needed drivers that are specific for the laptop. Not only did it fix the problem with the parallel port it also fixed a couple issues I was having with the default display device, which before did not allow me to view 1024 x 768. After I confirmed everything was working I decided to try installing Win 2000 again, except this time I did it as an upgrade and not a complete new installation. Amazingly everything still worked properly with the router controls.
Now I am all set. Once I figure out how this Mach2 software works of course.

Thanks