how to read data from USB port?

[q-nust]

I am using a USB cable. One end of the usb cable I have cut and connected to the slip rings and the other end is connected to the PC. I am unable to read the data from port. Can anyone tell me how I can read the data from USB port because there are no drivers and i am using the cable to take the signals in LabView.

[Ranjeet_Singh]

Which port you are taking about? is it com port?

[can_i_04]

Hello,

If your slip rings is an USB TMC device, is quite asy. You'll communicate with VISA boxes, and use the same process than wuith a GPIB device.

Check out this paper. It helped me : http://www.ni.com/white-paper/4478/fr#toc1

Regards

[q-nust]

it's not USB TMC, it has four signal cables and I want to convert one of the signal cable to USB cable and then access through labview!

[Joseph_Loo]

You have to realize what a USB cable is. It is a serial interface basically, you may be carrying serial bits across mutliple lines (http://en.wikipedia.org/wiki/USB). The serial rates do change on a dynamic basis. If you intend to use a single line and assume that it is a serial input, I think you will need to rethink the issue. Remember, some serial interfaces require a minimum of certain amount of line changes otherwise, it thinks that the data line is not being  clocked at the correct frequency.

[Intaris]

You can't do this.

You have no programmatic access to the individual pins on a USB port unlike an old RS-232 port.

You'll need to come up with a different approach.  Do you have an RS-232 port available?

[q-nust]

Yes I have RS232 port but through that the data rate would reduce. So Is it possible to use the ETHERNET cable and access this signal through RJ45 connector.

[Intaris]

No it's not feasible to misuse an Ethernet port for this.

An Ethernet or USB port do not replace a proper digital input card.

How fast do you need to sample the data?  Why don't you just buy a cheap Digital card?

[RavensFan]

You have not yet stated what is the signal you are trying to read.  What is on the other side of the slip rings?  Is there some device you are trying to communicate with?

Without you telling us anything about what this "signal" is supposed to be, all we can do is guess.  Someone has guessed you are looking at a digital input, but I don't see anything in what you've told us so far that would imply that.

[q-nust]

Yes it is digital input which i would be getting thats whyni wanted to use it as usb to pc so that I can later store the data in lab view.