The PTU’s home position cannot be reprogrammed. It must pass through the 0, 0 position during initialization. You can, however, disable this reset sequence so that the PTU does not move automatically upon application of power. The downside to this is the PTU will not know its absolute position. To disable reset, send RD followed by DS. After a power cycle, the PTU will not move from its power-down position. You can reset each axis individually (RP for pan, RT for tilt). To re-enable the power-on reset sequence, send RE followed by DS. There is no way to send these commands from the web interface on E generation models. You can, however, use the terminal program PuTTY to send serial commands via Ethernet.
If you wish to make relative moves without a reset, you must also disable limits by sending LD followed by DS before power cycling the unit. With reset disabled and limits disabled, you can command moves without a reset. The position of the PTU at power up will be considered 0,0. In this mode there is no protection against moving the PTU outside of its normal range of motion.