Solution
The built in serial ports on a CompactRIO (cRIO) will show up under VISA resources as
ASRL1:INSTR, ASRL2:INSTR, ... by default. This is the correct behavior, and if you select the corresponding port, it will use that port as the VISA resource. You can see the serial port naming under
Remote Systems >> Name-of-your-cRIO >> Devices and Interfaces and you can give a name to the serial port under
Settings as shown in the image below. This is where you can give the port a name of
COM0 or
COM1 if you would rather refer to your serial ports with those names.