[granado]

How do you opto-isolated the USB port?

BR
Antonio

I think you can select if it's active high or active low in one of the setup tabs. It should pull down very close to 0v if it's set up right.
You need to give more detail about the enable input circuit this connects to.
For example is it optically isolated or just a TTL logic level input. If it's optically isolated, you need to know the value of the series resistor and the forward voltage drop of the opto LED to be able to figure out what the drive really needs.
Do you have a datasheet you could post for the drive showing this information?
If you are still stuck, I'll brave the cold and fire up my system to see how it's set up in the control panel.
I had posted loads of useful stuff on the Brain Forum but it's vanished for the time being. You really need to opto-isolate all the enables and limits and make sure there are no earth loops. Don't forget that the USB connection from the PC will ground the 0V of your interface circuit! If you ground the 0v anywhere else you will have a whole lot of problems. I've opto-isolated everything including the USB port and now have a stable system. It's still only open loop but that should be fixed with the new update when it finally arrives.
Good luck with your machine.

[striplar]

This is an expensive thing to do. I bought a fibre optic extender for another application so used it for this because I was having so many problems. I had a quick look on the net for the one I bought but can't see it at the moment. There are others like http://www.blackbox.com/Store/Detail...solator/SP380A but that's very expensive.
I have since found that one of my limit switches was connecting 0v to earth which I think was the main reason for my problems. I decided to keep the USB isolation in place since I already had it.
I would opto-isolate everything else to start with and only go down the USB isolation route if you are still in trouble.
Don't assume that you are fully isolated until you can measure an open circuit between the 0V on the PC, the 0V on the interface board and the frame of your machine. Once you know for sure you are isolated, plugging in the PC will at least only ground the 0V at one end hence no loops.
I know this sounds like a lot of hassle but it's easier to do this in the first place than have to back over it and do it later.
The errors show themselves as spurious E-Stop error messages which cause the machine to drop out.
I think the Brain is particularly sensitive to mains born noise. Even with my setup, the Brain drops out to E-Stop if I turn on a Flourescent nearby. There's still more work to do on this.

[striplar]

I just found a link to the USB isolator I used.
http://www.ramelectronics.net/comput...prodM2100.html
there are two versions, I used the one that had a small power supply at one end ie a fibre-only connection.
Although this is expensive, it's the cheapest method I've found. Most of the others are hubs with 4 outlets which I guess is what makes them expensive.