First, I understand this is an old thread, and the OP may have already figured this out. But since I just had to go figure it out myself, I thought I’d post the solution I used for others who may be searching.
First, cabling: Serial consoles generally can be wired as Console or Terminal, and this determines which pin is Rx and which is Tx. So, a proper connection requires one of each, or if both are Console or both are Terminal, a roll-over cable is required (or a rollover RJ45 adapter, etc.).
While there are a lot of possible solutions (back-back CH340 or FTDI UART adapters with Tx/Rx crossed, etc.) I wanted something clean, easy, and not fragile. I ended up with two USB-Serial adapter cables branded as “oikwan” from Amazon, one with a male DB9 (ASIN B0759HSLP1) and the other female DB9 (ASIN B0BKJKYCJK). Both allegedly have an FTDI chip (it’s often counterfeited and I can’t confirm if these are genuine, but both cables are working fine with FTDI driver). Plug the DB9s into each other, one USB in the rb5009 and the other into the computer (or in my case raspberry pi).
The console connection does not come up automatically, which unfortunately makes it pretty worthless if you’ve locked yourself out of the router before configuring the console (as I had… oops). To bring it I used the following commands:
-
Confirm you can see the usb-serial cable
/port print
Should show something like:
0 1-1 usb1 1 Serial Console(#0) Auto -
Set baud rate to 9600
/port set 0 baud-rate=9600 -
Enable system console
/system/console/ add port=usb1
/system/console enable 0
After that, from a Linux system, you should be able to connect with:
screen /dev/ttyUSB0 9600 (or PuTTY, or whatever your terminal emulator of choice is).