Then I got 'caught' because there is none. From that I can assume that it worked, but I can't send or receive without something on the port.
OP1 worked in Qbasic to display 'caught' without hanging though. COM2 caused a Windows error, and 'caught' after I hit Cancel in the error box. XP normally blocks port access to NTVDM.
At least that is a way to test for the existence, but not much else.