Connect a wire to an IR receiver?

Hello,

I would like to control multiple devices with my computer. On the
transmitters page[0] it shows how to use the serial port, so I was
thinking to build something like this:

DTR >---(1N4148)---(R)---> device's IR cathode

1/ would it work?
2/ is it dangerous for my PC or my device(s)? I plan to connect 3 on my computer
3/ how long could the wire be?

Thanks.

[0] https://www.lirc.org/transmitters.html