Hello there,
I’m using 2 K8055 USB velleman cards for activating relais for a plasma spectrometer.
Sometimes the cards stops to work, but the program is not hanging.
After disconnecting the USB cables and restarting the program the both cards are working again.
I’m using microsoft visual studio 2005 and I using K8055D.dll
Is it possible that I send to fast commands after each other.
First I set an analog output , later almost in the same time I set 2 digital outputs.
I hope somebody has an explanation for this phenomenon.
Best regards Wouter 
Are you using the latest rev. 3 of the DLL?
We are using K8055D.DLL ver 2.0
You may try the latest version 3 too to see if the same problem persists.
I’ve downloaded the K8055D.dll ver:3.02 file from the website.
At home the card works fine with the project. >> with the most recent DLL >>> using the suplied cable.
I did the same tests yesterday with the old DLL without any problem.
What is the max. lenght of the USB cable we can use between the PC and the card?
In our laboratory we use a USB cable with a length of 2.0 meters.
The cable suplied with the card is too short.
It was not possible to use a cable of 4 meters because the cards didn’t work at all.
Perhaps the USB cable is to long or has other characteristics.
Best regards
Wouter
Indeed, the problem may be the USB cable.
It seems there are different ratings for the cables.
You may try using a cable rated for USB2.
The marking may be something like this: USB2.0 CABLE FULLY RATED 30V 80C
This kind of cable feels more rigid than the “normal” USB cables.
