how to know the amount of exchange of data between the PC and the machine?

edit

I am using the python language and I would like to know the amount of exchange of data between the PC and the machine. I followed this method for Single machine configuration [NetworkSetup] (http://wiki.ros.org/ROS/NetworkSetup)

the issue, when we bought the new robot with a WiFi device (max 59 Mbps). The robot's movement is very very slow, after that, we bought another WiFi device (max 850 Mbps) which improves the movement of the robot.

when I used an Ethernet cable, the robot was very very fast. So, I'd like to know the amount of exchange of data for buying another WiFi device which will transfer all data and robot moves free without a cable.

please help me or any suggestion?