Community discussions

MikroTik App
 
plzsendhalp
just joined
Topic Author
Posts: 2
Joined: Sat Jun 03, 2023 6:27 am

What's are my options for turning this empty serial port into a usable console interface?

Sat Jun 03, 2023 7:23 pm

Image

RB2011iL-IN

Should I use the 4 pads on the left? (RX/TX/GND/3v3), is this a viable option and would that be WG/G/WBR/BR in a 568B? What is the proper way to interface with these pads?

Or do I use the 10 empty holes labeled RS232. I have a COM header on an older PC with a male db9 ribbon cable to that port. I can use that to connect to those pins(I like to solder and have breadboards and wires for connecting).. but I thought serial is 9 not 10, so kind of confused there.

Can anyone help me with these two connections and point me to proper solutions? I would like to not spend more money and test my luck with what I have available to me here.

Thanks!
 
mada3k
Long time Member
Long time Member
Posts: 643
Joined: Mon Jul 13, 2015 10:53 am
Location: Sweden

Re: What's are my options for turning this empty serial port into a usable console interface?

Sun Jun 04, 2023 2:23 pm

Those pins is a 3.3V TTL-level UART port - not RS-232. You will probably damage the device is you connect a regular RS-232 port there. You will need a MAX232 or simmilar chip to make it compliant with RS-232.
 
r00t
Long time Member
Long time Member
Posts: 666
Joined: Tue Nov 28, 2017 2:14 am

Re: What's are my options for turning this empty serial port into a usable console interface?

Sun Jun 04, 2023 3:53 pm

The big RS232 connector pins go nowhere (there is missing level shifter IC under it) so that will not work. You can also see two small 0 ohm resistor links on the left under UART pads that route RX line to the pads (as opposed to level shifter IC if they were in other positions). So UART pads on PCB is what you want to use.

As for voltage, ALWAYS measure before you connect anything. Here it's given it will be 3.3V, but double checking it is always good idea. TX idles at high level, so when sending nothing you should measure 3.3V. When connecting UART to USB interface DO NOT connect 3.3V if it's generated from USB power. Some converters have link that allows you to run the chip from external power, in this case you can connect it to 3.3V from RB. But do not backfeed 3.3V from USB into RB, that would probably blow your USB to TTL converter chip. Also again double check your USB to TTL adapter actually outputs 3.3V voltage levels, because some say they are 3.3V but actually output 5V levels! Beware!

If you want to add TTL to proper RS232 converter/level shifter, there are boards available on Aliexpress etc. In this case it will be powered from RB 3.3V power supply rail, so you connect 3.3V,GND,RX,TX. If the board have CTS/RTS, you have to short these as these pins are not on RB (or make sure No handshaking is set on the other device).

Who is online

Users browsing this forum: No registered users and 5 guests