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Botroniks Arduino Hex code PC-side RS485 Converter with CP2102 Chip Compatible with Windows 7,8,10,Linux,Mac OS  
ARDUINO-side module RS485
PC-side module RS485
Link: 1-2-3
 
Link: 1-2-3
Link: 1-2-3
connections (click to enlarge)
 
need accessories
    
PC10: Arduino and PC communication (wired RS485) large length (up to 800m) -INFO!
Explanation enables: Wired communication (RS485) Arduino and PC over long distances ...
Required accessories: see above
For Arduino boards: NANO or UNO or MEGA
Arduino pins are used:
uc ATmega328p (NANO, UNO, ...): Adruino-side module RS485: D0/D1/5V/GND (unless otherwise stated in the project)
uc AtMega2560 (MEGA,.............): Adruino-side module RS485: D0/D1/5V/GND (unless otherwise stated in the project)
 
Electrical and practical notes:
Upload the code to the Arduino (in the classic way), and then connect the RS485 communication.
For long lengths, use a twisted cable
The manufacturer's instructions include a note for use up to a cable length of 800m. After that you need a signal booster!
Attention: This communication does not support all Arduino software on the net! Some time delays in communication are required. We did it here!
How to Upload code to arduino via RS485 communication:
This communication does not perform the function of automatic reset when uploading programs in Arduino, so entering programs into Arduino is not possible in the classic way.
However - Some notes for advanced users (try, but not recommended):
The remote Arduino needs to be powered.
Before uploading the code to the Arduino, press the Arduino reset button, activate the option to upload the program in the Arduino (Xloader - Upload) and after 0,5sec. (or less)- (1 sec. is too long) release the reset button! Maybe you will succeed!
Recommended to use an external voltage source 9V/1A (on dc plug or on VIN pin).
 
Some notes:
You can try communication with some of the offered codes (unless it is strictly stated that it is not RS485 communication)!
This way of communication is very important for serious projects where a large number of Arduino modules are connected to the same communication line and are called from the PC by using their unique password.