How to simulate a simple COM port signal (and take it into VB.NET)?

Question

Visual Basic

The task is this - there is a machine (the machine is controlled by the PLC, the normal access to the control system of which is closed). There is a computer installed on the machine, which displays the product specification and an electronic checklist for the machine operator. The computer and the machine are autonomous from each other and are not connected in any way at the moment.
There was a task to take a certain signal (yes / no) from the PLC of the machine and transfer it to the computer program. Since access to the PLC is closed, the electrician suggested taking a contact from the control relay and leading it to the COM port contact (there is a COM port on the computer, LPT is not). It was proposed to simply take the signal there is current / no current to one of the contacts of the COM connector.
Before outputting the signal, it was decided to test the program on a virtual COM port.
So the question is - how can you create a virtual COM port on a computer and use it to simulate a one-bit yes / no signal on one of the port pins?
Thanks

Answer 1

For similar purposes some time ago I used
Com port data emulator
and
Virtual serial port driver .