USB to RS232

[Happy]

Hi, we are a professional hand-held instruments manufacturer. I'm programming the software of PC interface. Currently, new bought notebooks got no COM ports but USB. Many new devices got this function " USB to RS232" to solve the problem. What I would like to ask is" By installing the new device, I often got the USB as a COM3, COM4...port. With my previous programming Language, Visual Basic, there's no problem talking between PC and meters from USB(COM3,COM4,...).
But, with Lab VIEW6.1, it didn't work. Some notebooks got a COM port. Unfortunately, this COM port works but USB."
Who could tell me what I should do in this field?
Thank you in advance.

[DiegoF]

Hi,

Every serial port recognized by the OS should be accesible from LabVIEW. If you have a driver that provides a serial port interface for the USB port, the main requirement is that the serial port has to be recognized by the OS. LabVIEW does not have a built in API to use the USB port.

For example, NI offers serial interfaces connected to the PC thru ethernet or USB. The driver for these devices handles the communication with the device (Ethernet or USB) and presents a standard serial interface to the OS. The OS recognizes this interface as another serial port.

Hope this information helps.

DiegoF.

[Happy]

Hi, many thanks for your comment. Yes, I do understand that serial ports have to be recognized by OS. I've checked the new device on Measurement & Automation Explorer->Device & Interfaces->Ports, I got COM3 installed already. Also, from the Control Panel->System->Hardware->Device Manager->Ports, I got USB Serial Port(COM3) installed. With Visual Basic program, COM3 works but LabVIEW. With AOpen AX6BC mother board, P2 350 processor, and 128 MB RAM, it works but with GigaByte GA-81DX(H) mother board, P4 1.6Ghz processor, and 128 MB RAM and other types of PC.
In fact, just one PC as above in our office works. The USB as COM3 serial port is recognized by those PCs which didn't work through COM3 but COM1 and COM2.
Those PCs got different OSs-Windows 98 SE, NT, Me
, 2000, and XP. Many thanks to you, anyway.