I have a project that stores the weight of the user based on his rfid with time.
So I am using an Arduino Ethernet Board, An RFID reader connected to interrupt pins(2,3), Real Time Clock with pins (A0,A4,A5) and to get the weight a 350 kg load cell connected to a sensor amplifier connected to board through pin(A1).
It is good and running it correctly reads the rfid gets the users weight and sends it to the server for saving.
But when I unplug it from my computer and place it where it should be deployed so now it is using a different power supply an ac to dc adapter(output 12v 1A) the values sent to the server are different. Let's say my ID is 123 the data now sent to my server is 24325 something like that. Even when I plug it back to my computer the reading is still wrong it reads 150.
But when I reupload my sketch the reading is correct again. Summing it up when I remove the power of my board and plug it back it the rfid reading changes.