Go to www.axis.com and look for your product page and under Support & Documentation the PTZ drivers are located for download.
Download the PTZ driver to your computer, see also the technical documentation and Connection examples for easier installation.
Connect the serial cabling according to the connection example
Go to the encoder PTZ, Driver Selection page and upload your PTZ driver, Pelco is preloaded.
Activate the selected PTZ driver by clicking in the Enable PTZ and set the correct camera id that match the settings on your camera.
If needed change the serial port settings under System, Ports & Devices, COM port.
For further help see the help pages in the encoder.