LabVIEW VI to read from Modbus Flow Meter

[pcxt21]

Hello All,

I am attempting to use LV with the Modbus libs to read/write information to a Micromotion Flowmeter. The meter is connected to the PC via a B&B electronics isolated RS485 to USB converter. VISA see the converter just fine. However every time I attempt to read from the meter I get an error "VISA:  (Hex 0xBFFF003E) Could not perform operation because of I/O error." despite my best efforts. I can't seem to figure you my problem, perhaps it has to do with how I'm addressing the meter? I have posted my code for further reference.

[Online_Courses]

Good Afternoon,

In order to get information off of a Modbus device you actually have to reach into the address where the data is updated.  I believe the connection between LabVIEW and a Modbus device actually requires the LabVIEW DSC Module.  You can try it out and download a 30-day evaluation from here.  DSC then allows you to bind shared variables to addresses on the Modbus device and then pass those values via an I/O server to your actual code on your host computer.  I hope this helps!

-Cody C

[K C]

Hi,

The error you get (I/O error) is not related to the ModBus protocol.

Somehow you computer does not want to talk with your USB device.

Do you see this port in MAX ? All drivers installed ?

Can you try to open this port with the standard serial config VI ?

Kees

[pcxt21 · Accepted solution]

Thank you, as it turns out my device had been improperly wired. I can now read the information I need from the flow meter.