VISA get resource name doesn't return USB serial ports

[jtauser]

We built an application on a computer that had an onboard serial port - COM1.  We put the option to change the COM port in the application.  We installed the built application on a computer with no serial ports, but installed a USB to serial converter that registers as COM3.  LabView does not see this port, even with a test application to return only the VISA resource names. 

We have verified that the port is good with another program (a Modbus simulator) and installed the latest VISA runtime v4.41 separately to no avail.

Any suggestions at further troubleshooting would be extremely helpful.

Joe T.

[Pnt]

If you put a VISA resource control, at the front panel, do you see the COM3 ?

Also you should verify your COM3 not with a software, but with hardware. Make sure it is ok. The simpler way is to transmit a few bytes

through hyper terminal, between two PCs.

[jtauser]

On the test application we put a resource control on the front panel.  It only shows LPT1.  As far as verification of COM3's existence, I checked in the Windows System-Hardware tab and it shows up both under Ports and under USB devices.  We did connect two computers together and verify functionality using Hyperterminal as you suggested.  It works this way.

I'm an old PLC guy learning LabView and working with someone who's done LabView since version 4.1.  I have a lot of experience troubleshooting serial communication problems- this one's really got me stumped.  I've ordered a serial card for the computer, but we really should be able to make it work with the USB adapter.  There will come a time in the not-too-distant future when a serial card won't be an option- laptops are alreay this way.

Joe T.

[Pnt]

I never had problems (with windows XP.)

Maybe try a differnt adaptor or reinstall the adaptor's drivers.

Also try rename to COM1.

Can not think of something else

[Matthew_Kelton]

When you open up Measurement and Automation Explorer, is the COM port listed there?  I have a USB-RS232 adapter and it is in the list, and shows up in my pulldown lst for VISA resources as well.

[Can_W]

Hello Joe,

If what Pnt and Matthew Kelton doesn't work, try typing in the name of the virtual com port itself. It should be along the lines of ASRLx::INSTR, x being the number stated in device manager. I would also make sure that you I/O Name Filter hasn't been enabled, the following knowledgebase describes this in more detail. It would be nice to know whether or not MAX can see the COM ports. If it can, you can also try a drag and drop from MAX to LabVIEW.

Hope this helps

[Kejoglo]

This is not an isolated case. I too am experiencing a very similar problem.

[Can_W]

Do you have a brand of USB Serial Adapters you are using? Does it show up in MAX? If anyone has any screenshots, it might help

[jtauser · Accepted solution]

My main application still isn't working, but now the small test ones are.

Here's what I did:

1.  Update my LabView 8.5 with the latest VISA runtime - 4.4.  This updated the Installer as well.

2.  Added the MAX Installer to the build.

3.  Added  the NI-VISA Configuration Support to the build

4.  Uninstalled the application and reinstalled it with the new install volume.

When I run MAX, COM3 shows up.  It also shows up in the Get Resources test application.  The simple test Modbus write program works, too.  I have a sneaky feeling that COM1 may be hard-coded somewhere in the main application; our next task is to find where the communications breaks down in our code.  The bottom line seems to be a lack of experience with the Application Builder on our part.

Thanks to all who contributed!

Joe T.

[jtauser]

A further update-

We got our application working after we realized that the text file which contained all the modbus address wasn't being put into the right directory- another installer configuration error.  On the development machine it was in the right place.  This resulted in the read and write matrices being zero size, which of course we didn't bother checking for.  I'm feeling rather retarded.  Thought this might be useful information for the underexperienced and a bit of a chuckle for those with battle scars.

Joe T.