OSDP Protocol

These pages explain how the OSDP protocol works on the wire, independent of any one implementation. Begin with the introduction to the control panel and peripheral device model, then dig into the supported commands and replies, the on-wire packet structure, and the PD capabilities that describe what a device can do. The FAQ collects common questions.

In this section ​

• Introduction — An introduction to OSDP (Open Supervised Device Protocol) — the control panel and peripheral device model, the RS-485 bus, and secure access control.
• Commands and Replies — Reference for OSDP commands and replies — the full message set exchanged between a control panel (CP) and peripheral device (PD) on the OSDP bus.
• Packet Structure — The OSDP packet structure on the wire — header, security block, command/reply data, and CRC/checksum framing for the Open Supervised Device Protocol.
• PD Capabilities — OSDP PD capabilities — how a peripheral device reports its supported functions so a control panel can discover features before driving the device.
• FAQ — Frequently asked questions about the OSDP protocol — secure channel, interoperability, RS-485 wiring, addressing, and common integration questions.