ports and interrupts...

Hello All! Few com ports and interruptions ;) Modem (int) transferred to COM2,IRQ5 One com port is occupied by the uninterruptible power supply. There's one more left. But, firstly, I need a null modem, and secondly, an infrared port. If you enable IR mode for UART-2 in the BIOS, then it is no longer like a regular port. does it work? And if you plug in some kind of cartoon, then what to do with interruptions? For example, the modem did not work for me if its interruption was occupied by com4 (although in there were no errors in the device manager), so I had to use a modem on com2/irq5 hang... Best regards, Evgeniy.