metropat

I Have a DM SD Advanced DVR and would like to connect a Dennard 2060 PTZ camera to the DVR. From what I can see on the Dennard 2060 it has three wires for a RS485 conection (earth/yellow/green), do I have to purchase some kind of converter to enable me to connect these wires to the RS232 (D type)connector on the rear of the DVR. Any help would be appreciated, thanks in advance Happy New Year