PelcoP

PelcoP, or Pelco-P, is a serial communications protocol used to control PTZ (pan-tilt-zoom) cameras. Developed by Pelco, it became a widely adopted standard in CCTV installations and is typically implemented over asynchronous serial links such as RS-232, RS-422, or RS-485. The protocol is designed to carry commands for movement, zoom, focus, iris, and presets, enabling centralized control of multiple cameras on a single line.

A Pelco-P command frame consists of seven bytes sent in a fixed sequence. Each frame begins with a sync byte of 0xFF, followed by the device address, two command bytes, two data bytes, and a checksum. The checksum is computed as the sum of the address, command bytes, and data bytes modulo 256. The address field enables controlling one camera or addressing multiple cameras on the same serial segment.

Operation relies on regular transmission of frames, typically at a modest rate (often around 10–25 frames per second) to ensure smooth motion. The data bytes carry the parameters for the requested action, such as pan/tilt direction and speed, zoom level, focus, iris, or a preset call. WhilePelco-P and Pelco-D share the same 7-byte frame structure, they use different command mappings and data encodings, meaning devices must support the corresponding variant.

Pelco-P remains in use in many legacy security systems and is commonly compared with Pelco-D. Its simple, vendor-neutral frame format contributes to broad compatibility, though modern deployments increasingly rely on IP-based or API-based control alongside or instead of serial PTZ protocols.