I am trying to connect a encoder to a motor controller which runs very close to the motor that it controls (30+ amps). Due to the risk of high EMI of the motor inducing on the encoder signals, we send these signals differentially (RS485) over an SF/UTP cable. Currently, the shielding of this wire is connected directly to the ground line of the encoder. The figure below shows the current wiring:
I am not sure if this would be the proper way of wiring these signals under these circumstances. I am a bit worried that the groundloop causes ground noise and thus ruins the proper grounding that the encoder requires (it's powered by 5V and can take up to 1V of fluctuation worst-case, but better grounding is absolutely preferred). I've seen solutions where one side is connected with a cap, however this is not ideal in my case because I do not really have any room for this.
My question in a nutshell: would the groundloop in this case possibly cause issues? Note that the currents to the ground plane are limited to <250mA. Or are there other solutions that are more suitable for my case? Connecting the shielding to the frame for example.