I'm currently doing a microcontroller project that requires a serial port, but for testing purposes, I require two serial ports and terminals working with both of them.
My computer has one native serial port with no issues.
I tried using USB to serial adapters and some partially work while others do not work at all.
Now I'm trying an older PCMCIA serial adapter and I couldn't get it to work despite the various ideas presented on the internet including from here: http://www.electronicsfaq.com/2010/02/getting-serial-port-to-work-under.html
I also followed the instructions presented on the included driver CD and I'm told "/dev/ttyS4" doesn't exist when I run the executable. Perhaps I should somehow create it?
I also executed "setserial /dev/ttyS* uart 16550" on an existing /dev/ttyS* device that matches the same IRQ and port number as what the adapter provided. I used commands "setserial -gv /dev/ttyS*" and "lspci -v". The system happily accepted the uart assignment no problem.
When I executed "screen /dev/ttyS* 9600", the system locks up in graphical X window mode and I have to manually restart the computer.
I tried the same procedure again without loading the X org graphical system and I constantly get a message from serial8250 driver stating there's too much work for the same IRQ the PCMCIA card is using.
I also noticed that my wireless network card is also using that IRQ but during the tests, I wasn't even using that network card.
What's the best thing to do?
Should I just somehow create a /dev/ttyS4 with special properties and just load the driver? or should I load some different driver? or should I disable other parts of my system to get the adapter to work? or is my only real option to buy a more ancient laptop with two serial ports built-in?
My linux is slackware 13 (kernel 2.9) and I'm running a dell laptop.