> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/knowledge-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.security.gallagher.com/knowledge-hub/products/cc-software/configure/interface-options/open-supervised-device-protocol-osdp.md).
# Open supervised device protocol (OSDP)
Understand OSDP support, wiring requirements, and Controller 6000 capacity.
**OSDP** is an access control communications standard developed by the [Security Industry Association (SIA)](https://www.securityindustry.org/industry-standards/open-supervised-device-protocol/) to improve interoperability among access control and security products.
OSDP is best explained in contrast to the **Wiegand** interface protocol it is replacing. Wiegand is over 40 years old. It is unencrypted, so those card systems are vulnerable to hacking. It is also unsupervised and uni-directional, and readers cannot be daisy-chained to each other. Each must wire back to the controller over a limited distance using the home-run method.
Because proximity card protocols were all proprietary, no interoperability existed between brands. OSDP was developed as a non-proprietary interface specification that can be implemented without restriction. It allows security devices such as card readers, controllers, and I/O boards to talk to each other through a bi-directional RS485 channel.
> ⚠️ OSDP, like all RS485 communication protocols, does **NOT** support **Star** connected wiring. Always run OSDP in **Daisy Chain** configuration.
## Which Gallagher products support OSDP?
* **OSDP version 2.1.6** is available from Command Centre **v7.30**.
* OSDP connectivity is available on each of the two RS-485 ports of the **Controller 6000 only**, with support for up to **16 OSDP readers per controller** over a maximum of **10 controlled doors**.
* 8 OSDP readers per RS485 port.
* Gallagher's implementation of OSDP supports OSDP-enabled card and card + PIN readers.
> 🧭 **Where to start**
>
> * **Adding a device to the bus?** → [OSDP - Setting up an OSDP device for the first time](/knowledge-hub/products/cc-software/configure/interface-options/open-supervised-device-protocol-osdp/osdp-setting-up-an-osdp-device-for-the-first-time.md)
> * **Looking at the other protocol interfaces?** → [Interface Options](/knowledge-hub/products/cc-software/configure/interface-options.md)
OSDP - Setting up an OSDP device for the first time
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