I'm new in electronic and started a weather station project that send data via RS-485, the shield in cable that connect weather station need to be grounded, i wanted to ask shall i ground it to my microcontroller GND or the earth ground, and why?
thanks before 
ktannady:
I'm new in electronic and started a weather station project that send data via RS-485, the shield in cable that connect weather station need to be grounded, i wanted to ask shall i ground it to my microcontroller GND or the earth ground, and why?thanks before
Welcome to the Arduino forum. There are sticky posts that tell you why a ground is important and sometimes necessary for your project to work properly.
A shield is only a shield if ONE end is connected to the ground or common connection used by your project. If both ends are connected, it becomes a conductor, not a shield. I hope your RS-485 cable has a separate wire that connects the grounds at each end for RS-485.
Your weather station should ultimately have a real earth ground through the power supply connected to the mains power. But if not, should still operate ok.
Paul
If it is outside be sure the shield (drain) is connected to earth ground only at one end the other open. When you get sparks in the sky guess where they want to go and how they will get there. EMI will die when buried in the ground as well. I can only guess as I do not know what it looks like or where it is going to be mounted. I did all my outside sensors wireless so that eliminated the problem with sky sparks blowing stuff up but it still causes communication interruptions.
Idahowalker:
Common ground and why you need one - General Electronics - Arduino Forum
Thanks for your reply, now that i read the topic above, im curious that the RS-485 only use 2 cable for A and B, but don't have the same ground that connect the transmitter and the receiver still can communicate with each other.
I'm sorry but i have read some documentation about the RS-485, but still cannot understand all of them at once. i gotta spend more time for this, thank you.
Paul_KD7HB:
I hope your RS-485 cable has a separate wire that connects the grounds at each end for RS-485.
Thanks for your reply, this is what my cable looks like, it consists of 2 cable for A and B and a shield that wraps them. and the shield is what im going to ground to the earth ground (i think) but i've seen some PowerMeter that use RS-485 has a terminal called shield, i wonder where does this terminal connected to because i don't have any on my own.
Paul_KD7HB:
Your weather station should ultimately have a real earth ground through the power supply connected to the mains power. But if not, should still operate ok.
my weather station is powered by a USB phone charger, so i think there is no earth ground connected.
my weather station works perfectly in my workshop, but after testing in field, it sometimes didn't respond, that's why i started to think about the shield.
gilshultz:
If it is outside be sure the shield (drain) is connected to earth ground only at one end the other open. When you get sparks in the sky guess where they want to go and how they will get there. EMI will die when buried in the ground as well. I can only guess as I do not know what it looks like or where it is going to be mounted. I did all my outside sensors wireless so that eliminated the problem with sky sparks blowing stuff up but it still causes communication interruptions.
Thanks for your reply, i will learn more about the wireless like the ESP and LoRA, may i ask what did you use to send the data wireless-ly?
Thank you, for all your reply, im sorry for a lot of question that i asked, i have a lot of question in my head rn, that is what encourage me to start to use the Arduino forum after a year using Arduino myself
I suspect the power meter shield connection is for the shielded cable for a hand-held device.
Paul