Hi, I am having problems with NI-VISA (Ver 18.0) and the CP210x SI-LABS VCP (virtual COM port) driver ver. 10.1.9 in a LabVIEW 2018 application. The application receives serial data from two contamination monitors over USB via two virtual COM ports. The app typically works fine for several days, but eventually one of the the COM ports stops returning data. I see that when this happens, in NI-MAX, under Devices and Interfaces, in the Setting pane for the COM ports, the Port Description field is set to Unknown (when working correctly it displays the name of the driver). The COM ports still show up in Windows Device Manager. The only way I’ve found to restore the drivers to working order is to re-start the computer, as restarting the app (.exe) won't fix it.
Wondering that I might be corrupting the driver by setting some parameters that might not be supported, I pared the property nodes for opening the COM ports down to Baud, Data Bits, Parity and Stop Bits, however this did not fix the problem. I am not writing to the port. The program uses a VISA Read vi in a loop, where the Byte Count input is set to Bytes at port to receive a message of 80 or so bytes sent out every 20 seconds.
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Has anyone else run into to this or know what might be causing this? Would updating to VISA 20.0 help? Thanks for any help on this!