Hello,

i have to create a virtual com device which is listening on a com port. There is an existing software which
connects to the com port and sends out commands and receives some data. Now my software should act
like the real device and i was wondering how to do this.
Is it possible to read and write on one com port for more than two programs(i don't think so, but perhaps... )
or should i connect each program (the existing one and the emulator) to a ttySx device and then somehow
connect both of these ports?
If this is possible please let me know. I found something about serial/net redirection, but i think thats not
suitable for my needs.

Thanks, Mike

I think that the simpliest solution is to write a daemon that opens something (Unix domain socket looks like the best solution) for the existing software to use. The daemon also opens the real port and copies the data between the two.

You can also always make it a driver, but that's (a bit) more complicated.

Hello,

thanks for your reply Mara. The problem is that the existing software can only connect to a com port. So
how can i tell the software to access the domain or tcp socket? With these serial port to tcp converters?
I can't rewrite the software because it's closed source and so i'm bound to a com port.
Let's say i use such a serial2tcp converter, can this tool listen on a com port where only software has
access to? As far as i understand you can only reroute serial data from serial devices to a tcp socket.
But i need the data which the program sends to the com port and i want to send data back to the program
without using any external cable or so.

Thanks, Mike

I'm not thinking about TCP/UDP sockets. It would require a rewrite. Instead, using Unix domain socket requires you only to force the program to connect to /tmp/vport (or a different name) instead of /dev/ttyS0 (or similar). If the file is in fact a socket, basic operations should work. Things like changing speed etc would cause problems, unfortunately. But first check if it allows you to connect to something differnet than /dev/ttySX.