Communicating to a USB device through a virtual com port

I have a device connected to the windows pc through an usb port. I was told by the manufacturer that it uses a virtual com port to communicate. The problem is that since unity 2017 the ftd2xx.dll won't recognize the device as connected when building a standalone. In the editor works fine. Also in Unity 5 it works fine too even when building a standalone.
Also in Unity 2019 it doesn't work even in the editor and I see in the debugView the "native extension for windowsstandalone target not found" like shown in the attached image.
I would really appreciate if anyone can give me some insight on this,
thanks!

 

I know you PM'd me about this and I said create a thread. Currently I'm at work so I can't go in depth right now, but in the mean time...

I'm assuming your virtual com device is emulated as serial device in nature. Have you tried using the System.IO.Ports.SerialPort class:
https://docs.microsoft.com/en-us/dotnet/api/system.io.ports.serialport?view=netframework-4.8

Note, you need to be using full 4.x compatability for this.

 

Hi,
I have the same issue. I have a 64-bit native dll that communicates with serial USB (which uses ftdx22.dll). On Editor it works fine but when i generate a Build it doesn't connect to the device, the ftdx22 is not capable of opening connection.
I have tried adding the dll and ftd2xx on Plugin folder and also tried adding them on executable folder, both don't work on Build. On Editor everything works.
This issue happen only with Unity versions since 2017. With Unity 5 the dll works on Editor and Build.
Did something change between Unity 5 and 2017 regarding Build settings?