Nugget: 1 of n : GEtting started with USB communication via VISA

[danil33]

Hi Intaris,

                 Iam using a pendrive.Configured properly everything to read from a USB raw device.But showing an error  '
VISA:  (Hex 0xBFFF0072) The resource is valid, but VISA cannot currently access it.' Why VISA can't access it??Plz reply.

[rolfk]

A pendrive is most likely installed by Windows as a removable storage device. I'm not sure VISA is able to claim that device from Windows as Windows likely is installing this in quite a low level way.

[smercurio_fc]

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@danil33 wrote:

Hi Intaris,

                 Iam using a pendrive.Configured properly everything to read from a USB raw device.But showing an error  '
VISA:  (Hex 0xBFFF0072) The resource is valid, but VISA cannot currently access it.' Why VISA can't access it??Plz reply.

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STOP creating multiple posts for your question!

http://forums.ni.com/t5/LabVIEW/Requirements-to-read-from-a-USB-port/td-p/1959445

[smercurio_fc]

STOP creating multiple posts for your question!

http://forums.ni.com/t5/LabVIEW/Requirements-to-read-from-a-USB-port/td-p/1959445

[Balu_EMB]

I'm new to Labview, I trying to develop USB RAW drivers using VISA as per the below link..!

http://www.ni.com/white-paper/4478/en; I'm working on the windows 7 OS.

The issue is....: I could create the .INF as directed in web page above; I could not see the .PNF file getting created after right clicking the on the .INF file and select install option..

I don't know whether problem is with OS or the .INF file...

[Intaris]

Please post in a seperate thread and I'll answer you there.

[Balu_EMB]

Hello I have posted one before in below link;

http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/Can-t-create-PNF-file-from-INF-file/td-p/2158...

Can you pl reply me there...???

Under Title..

Can't create .PNF file from .INF file

Thanks.. 

Balu...!

[Top24]

Hi, I started working on LabView right now and it is my first visual programming and I'm trying to understand some basics of LabView communications with USB and having loads of problems finding the information I'm needing.

My problem is this: I already have a PIC processor to control a thermoresistor and it has a HID USB connection to PC. I'm trying to understand if it is possible to use windows default drivers to threat my PIC has a generic controler and use LabView to acess it proprieties without creating my own driver in LabView driver Wizard.

If the only possibility is using VISA and driver Wizard in order do connect with my PIC how can I do it?

Thanks, Top24

[LamD.]

Hi,

here's a Knowledgebase that should fit your needs:

- Programming HID Compliant USB RAW Devices in Windows Vista using NI VISA

another possibility would be to use a proprietary driver DLL: If there is a driver DLL available you could try and call it using LabVIEW Call Library Node:

- Tutorial: Configuring the Call Library Function Node to call a Simple DLL

Best Regards,

Lam

 

[Top24]

Hi again, thanks LamD. for your previus answer, as I said before I'm realy new in LabView so I would like your advice in something..

I want do control some heaters in my software but I don't realy know how to do that, I think there is some NI module that connects USB to my program and using PID it turns ON/OFF my heater as I want, my problem is that I searched around the Web and I can't understand how to use PID and USB and a NI module to control my heaters 😕

Sorry if my doubt is stupid 😕

[Steven8R]

I found this thread by searching "USB and PIC". Lots of great stuff here. Downloaded and started looking at the USB2 specs, after some Tylenol and a stiff drink I gave up 😛

I think my question relates to this thread, so posting here. I have designed many different "boxes" over the years using 8 & 16 bit MCUs. I always had an RS232 port on them. Lately though I am really seeing the need for a USB port. Some of the PICs I use have USB built in. So I dusted off a development board, got it working with a very basic "put out what you receive" loop-back.  I built a test .vi and it works great. Went through the process of creating a RAW .inf using the Driver Wizard.

So now what I am wondering what is the best way to "handle" the USB side of things. Showing my age here - I used VB6 (and lately LabView) to create a GUI.  I am not sure how "portable" something like this is. Say I made 10 widgets and sent to 10 people, they all would have to have to have LabVIEW installed to run the Driver Wizard, because even though the VID&PID are the same, the USB port is different?

I guess what I am asking is what is the process for creating (or tweaking the USB info in firmware) a "real" USB driver, such that I plug in the widget, Windows loads a "standard" USB driver with my VID&PID that LabVIEW sees in VISA without the need for a custom "Driver Wizard" approach?  Would I have to call the .dll (I forget what it is called) in LabVIEW with the VID&PID info direclty? I sense that you have delved enough into USB (and paid the price lol) to know what I am trying to ask 😛 Maybe the right term is "how to expose the USB to LabVIEW most efficiently?

Any FTDI RS232<>USB adaptor pops up as a COM port, would be wonderful if I could figure out the same thing, or how to communicate directly via the .dll.  

Any pointers would be greatly appreciated and Kudo'd!!

Thanks,

Steve