There is a section in the amplifier's manual which states:
First of all above terminal 5 in the amplifier's screw terminal which is called Screen/Ground is not internally connected to supply GND or output signal GND ect.
The load cell on the other hand has many wires to be connected to this amplifier One of the wire is connected to the load celløs metalic surface. Lets cal this wire load cell screen LC_S.
When I connect the load cell to this amplifier properly I have the follwing observation:
If I connect the load cell's screen wire LC_S to terminal 5 of the amplifier, the noise is typical.
But if I do not connect the load cell's screen wire LC_S to terminal 5 of the amplifier, there is 50Hz noise added(observed at the amplifier's output) which is bigger than the typical noise.
Why does this 50Hz noise disappears when I connect the metallic surface of the load cell to the amplifier's screen terminal? I don't get this because this connection do not have any eventual connection to the earth. The load cell is floating and the terminal 5 is not wired to anything(I checked with continuity test). Im really curios what makes this noise to disappear.