Generally, the 485 control line will be connected to the hard disk video recorder or matrix. The ball machine will have a dial jumper or something, which is to set the address of the ball machine. The address in your system cannot be duplicated. This address is the destination address of the control signal. There will be a row of ports behind the video recorder and matrix. You can connect them to D+ and D-, and the two ends are+-corresponding. After the connection is completed, it is necessary to set up the video recorder and matrix, so that the video recorder and matrix can know what the address of this camera is (that is, it is set on the ball machine) and what the protocol is. If you don't know what the protocol is, please select Automatic. If it doesn't work, you have to look at the protocol of the camera, just correspond.