RS485 Communication Issue

Using Arduino Project Guidance
1

Hello,
I am trying to build RS485 based communication project for multiple arduino, to begin with i used several example over internet and having similar kind of issue. My issue is Master always sending message but slave never receives it or not printing it in serial monitor (I suspect serial monitor because both RX and TX lights are ON on slave), another trouble is if my program is running then i am sending back communication to master now master says it received communication back but it doesn't receive any data in it. You can see below image for reference of my serial monitor data. I have made few changes in code, attaching those along with other example i tried...

Code I am using -

Nick Gammon's excellent article on RS486 including libraries and multidrop example

1766×1002 115 KB

I am newbie to Arduino and trying to learn, so for sure i might be missing something simple. Also i am not using breadboard to connect all GND. I just used normal wire and solder them together. Other are connected to Nano and RS485. Below are the connections i am following..

RS485_Sender.ino (2.99 KB)

RS485_Responder.ino (2.64 KB)

2

After debugging more i noticed below behavior, if i remove slave RX cable from RS485 i can see data being printed with some reverse question mark and x.

1784×1055 124 KB

3

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html . Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom.... :slight_smile:

4

Make sure ‘both’ the TX and RX baud rates are set to the same value.

example 9600 baud