Here is the installation manual for the Encom DX7 Pan Tilt Unit.
Manual PT DX7 english V1.1 - Kopie.pdf (3.6 MB)
The installation and configuration guide explains how to set up soft buttons and IP Notify messages for the camera to control the Pan Tilt head but if you wish to send API commands from another system it would be in the format of
http:///control/rcontrol?action=putrs232&rs232outtext=%FF%01%00%02%01%00%04
See the command list included in this attachment for the exact commands available.