When setting up a GeoVision system we built our own video server. In order to control the PTZ Pelco dome cameras we are using a RS-485 to USB cable. While doing research here I noticed that there are GV-COM and GV-Net cards that have data converters. Are these necessary to control the cameras, or is my RS-485 to USB cable sufficient? I was wondering if these cards are doing some with the data from the GeoVision software before sending the control data to the PTZ camera.