Using +5v DC from Xylotec for I/O Board

[webgeek]

I want to optically isolate my computer from the CNC controller card. This seems a nice and capable solution:
http://www.cnc4pc.com/Parallel_Port_Interface_Card.htm

It requires two 5v inputs (if you share power supplies, you lose isolation on the ground - bad). One 5v input is from a hacked USB cable that connects to the computer. The other input can be from a power supply or some other device. Go here to see the wiring diagram provided by cnc4pc. According to them, only 950mA are required to power the controller side of the card.

My question is this: can I use the 5v output from the Xylotec to power the card? The docs from Xylotec specifically state:

The GND & Vcc (+5VDC) available on the right hand side of the board can be used to pull limit inputs high through a 10K resistor. It is not intended to drive other devices.

This would lead me to believe you can't use it, which is unfortunate but acceptable. I just wanted to check to see if that warning isn't just there to prevent someone from trying to power a higher-input load rather then a simple I/O board.

Thanks!

Mike

[GaryCorlew]

I also bought a card from cnc4pc, I use the +5 from the xylotex card to power it. No problems so far, its been that way for almost 1 year

[webgeek]

Nice, thats good news. I didn't feel like adding in a second power supply just for 5 volts. Are you using the same interface card I am? If not, can you let me know which one you use? I'll just compare the load requirements to be doubly sure. Thanks!

[GaryCorlew]

I am using the C11 card, Mine must be rev1 because I see that the output port is in a different spot.

[Coogrrr]

Originally Posted by GaryCorlew I am using the C11 card, Mine must be rev1 because I see that the output port is in a different spot.

why are you 2 using these cards? My Xylotex connects directly to my p-port and I can run from mach 3 all 4 axis. I dont want to screw up my stuff so can you tell me why this card is used?

Sorry if this is a total newb question.

[webgeek]

As soon as you make a minor wiring problem with a limit switch (or any other issue/short) you can roast your computer through it's parallel port. The second board is design to isolate the computer from the controller board. Basically an added piece of insurance. You will fry a cheap chip on the isolation board rather then a several thousand dollar computer. In my case since I plan on using my high-end desktop for everything the insurance is well worth it

[Coogrrr]

Looks like i am ordering another part.....

[GaryCorlew]

I agree with webgeek 100% While you will hear that it has never happened, but for me I didn't want to be the first

[webgeek]

Actually, I incorrectly assumed the CNC controller boards WERE opto-isolated until I read on here or another CNC forum about someone wiring a limit switch improperly and frying both their motherboard and hard drive controller. Also, any of the good boards will have LEDs to show activity, making it easier to diagnose problems (or so I assume).