Communicating USB using Labview VISA

[sf5959]

I have a USB RAW device that I am trying to communicate with using labview VISA. I have had success with setting up the driver and I am able to get information from the device such as serial number, etc. When I try to use the VISA read and write commands, I have no success getting the information I want. The commands are simple: R SP<CR><LF> is a read set point command. The only thing I do get back for every command I try, is a 2 byte message "01 60"hex.

If you have any suggestions, I would appreciate it, thanks!

jeremy_diehl@waters.com

[Christopher_T.]

Hi sf5959,

Are there any errors when you try to send out the R SP<CR><LF> besides just receiving "0x0160"? Also, how are you putting in the termination characters into the VISA Write?

Thanks!

[sf5959]

Hello Chris, I do not receive any errors and yes, I am including the termination characters in the string.

Here is what I get when I use a USB port monitor when I send out this string.

Thanks!!

[94] URB_FUNCTION_BULK_OR_INTERRUPT_TRANSFER (SUCCESS/0x00000000) 20101119150318.131 (+0)
Pipe handle: 0x87696D6C
Transfer flags: 0x00000002 (USBD_SHORT_TRANSFER_OUT, USBD_SHORT_TRANSFER_OK)
Transfer buffer MDL: 0x88C47208
Transfer buffer length: 6
Bytes transferred
0x0000: 52 20 53 50 0D 0A (R SP.. )

---

[94] URB_FUNCTION_BULK_OR_INTERRUPT_TRANSFER (SUCCESS/0x00000000) 20101119150318.147 (+16)
IRP status: 0x00000000 (STATUS_SUCCESS)
Pipe handle: 0x87696D6C
Transfer flags: 0x00000002 (USBD_SHORT_TRANSFER_OUT, USBD_SHORT_TRANSFER_OK)
Transfer buffer MDL: 0x88C47208

[Dennis_Knutson]

What is the device? Do you have the documentation from the vendor on using USB RAW? Can you attach it?

[sf5959]

The device is a chiller manufactured by Thermo. They do not have any specific documentation concerning USB communication, only a short command set description. I grabbed the two pages dedicated out of the manual and created a quick, but poor quality PDF, and attached it.

Thanks!!

-Jeremy

[Dennis_Knutson]

It says its a serial device. Why would you use the driver wizard to create a USB RAW interface?

[sf5959]

That command set is for both RS-232 and USB. The chiller I have only has a USB port.

[Dennis_Knutson]

Which probably emulates a serial port.

[sf5959]

I'm not sure what you mean by "emulates a serial port"? Its a USB port.

[smercurio_fc]

Some devices use USB chips that register themselves as serial ports to the operating system. So, even though you plug in via USB, you will also see a serial port in the list of devices in the operating system. This means that as far as your application is concerned, you'd be talking to a serial device using serial port communication functions. You should not have created a driver for a USB RAW device. If you did you must remove/unintall it.