RS485 and some Arduinos

Hello all,

I nedd a good tutorial to connect some Arduinos with RS485, in my interface I am using the max485.

thank you for the help,


You can follow the link:

Sorry, it´s in spanish


Igor R.

Thank you very much Igor, that solved my problem.

(PS No problem I speak spanish)


I just started working on an RS485 design myself, using newsoftserial9.

I just built an RS232-RS485 adapter for the PC. I'm looking to string a number of devices together using the multi-drop capabilities of RS485.

I don't speak Spanish... so if you end up doing things you can share... that would be great.


maybe this can help you


Thanks... but he was being real sketchy about how he got it working... and for some reason his routines would cause my arduino to reset when used with newsoftserial9. I didn't have the desire to debug the reason why... so I started over. (He was an inspiration though).

Igor's stuff is much more interesting.


If I have some free time, I´ll traduce it.


Igor R.

"...Igor's stuff is much more interesting."

I agree with you Pwillard and Igor is very, very helpfull.

I am discussing some ideas with him in the international forum.



I´ve just finish one example. There are 3 Arduinos, one master and two slaves.
The slaves have a led in their pin 13.
The control of switch on/off is with 2 buttons from Master.

Here you can see a photo:

And the video working:

A diagram of the protocol:

It´s based on a proffesional machine:

It´s important the lenght of the conecttion from transceiver (MAX485 or 75176) to the bus be as short as possible. I always do my connections like the photo (black and white are the bus).

Now, It´s easy do my own functions to control an arduino network. I´ve prefered use something based on a professional machine, because for sure my applications will be easiers.

To see the data in the bus,you can use RealTerm It´s free and you can see hex and ascii data.

You can see the code of this example ==>


Igor R.

Igor: Nice Work!

Do you have a schematic view of your 485 converter? I can recognize the max485 and a resistor but what is it on the top right corner? is it a voltageregulator?


It´s just a jumper to add/remove the resistor...


Igor R.