Capture from a PC based BACnet device?

edit

Do you mean some technique like this:

https://www.netburner.com/learn/how-to-create-a-virtual-serial-port/?srsltid=AfmBOooBf9pdPJgR6QvmEAYJNdbZYsEag4BuEMsuZUnU9sbhEQs7FdV0

Then yes if the virtual com port uses the network as its underlying transport medium. You would determine what protocol and ports that are in use and configure Wireshark to capture on the appropriate interface, filter, and the serial data would be available.

I have used this SW to do this when I needed to see the raw serial bytes but had no access to them otherwise and we just know that Wireshark does a great job at displaying this kind of information: https://github.com/cminyard/ser2net

Note that we are not pointing Wireshark to capture on the virtual or physical com port directly; we are making use of the fact that the virtual com port uses the network to move data. We are forcing our serial data across the network so we can capture it via Wireshark.

Also this device has (well, used to - its been a few years) a driver that can dump the serial bytes into their small debug tool that is provided. Avoids extra moving parts of forcing serial traffic through a network for analysis.