RS485 communications using USB to RS485

[DarrenW]

Hello,

I am trying to write a labview vi to interface with an RS485 device using a USB to RS485 converter. This is the converter that I am using: http://www.serialgear.com/USB-to-Serial-Adapters-(RS232,-RS422-&-RS485)-USB-COMi-M.html

I can't get the VI working. I have confirmed operation, baud settings, and wiring of the RS485 device using TeraTerm. 

I have tried using the two attached VIs. One is from NI (202314.vi). It gives me an error "Error -1073807330 occurred at Property Node (arg 1) in 202314.vi" 

I have done some googling but can't figure out how to resolve that. I should note that I don't see lights on either the RxD or TxD status indicators for this.

I have also used a VI that I wrote (RS485 Test). It doesn't return any errors but it also doesn't seem to do anything.  I don't see lights on either the RxD or TxD status indicators for this.

When I test with the NI MAX using the VISA test panel, it seems to work. It says it returns five bytes. However, only the TxD light is indicating--the RxD isn't lighting as it does when I successfully communicate over TeraTerm. 

In terms of other relevant info, I am communicating at 9600 Baud, 1 stop bit, and parity set to None. I have a decent amount of Labview experience but absolutely zero communications experience. 

Any help would be appreciated! Thanks in advance. 

[Tuco100s]

The error you are getting is directly related to the property node after the configure serial port VI, it seems like the inputs are not accepted by this VI. From what I've seen an option would be to use Visa Open instead of Configure Serial Port and that way you don't have to use the property node. 

[DarrenW]

Interesting thought. I ended up getting this working last night. I found the Simple Serial example and used that. That also uses the Configure Serial Port but doesn't throw an error. I have no idea what the issue is still but have it working. 

[labview.x.88]

ERROR is from USB to RS 485

Please use this link labview usb to RS 485

https://www.add-furnace.com/furnace-accessories/yamataha-usb-to-rs485.html

Support LabVIEW Modbus library(Modbus RTU/ASCII)