OSDP stands for Open Supervised Device Protocol developed by leading security industry and owned by SIA – the Security Industry Association,

The protocol is recognized as a standard by NIST and in final stages to be registered as IEC-60839-11-5

The protocol intention is to provide more reliable and secured communication between Access Control controllers (Panels) and the readers. It is structured on the RS485 infrastructure and provide bi-directional communication between the controller and the reader, unlike the one-way Weigand protocol. By utilizing bi-directional protocol, it allows for communication error corrections, more information transfer, encryption and more. Version 2.1.7 is the current version (2020)

OSDP is design to allow the use of compatible devices across platforms and vendors. 

Advantages of OSDP

  1. Less wiring – RS485 2 wires compared to 4 wires in Weigand, and the ability to run multiple readers on the same BUS (Multidrop)
  2. Longer distance – RS485 allows for up to 4,000ft. (1.2Km) distance. Weigand is usually limited to 200-500ft. (60-150m)
  3. Communication Quality – the protocol allows the message receiver to ask for retransmit of information if message did not arrive correctly. Weigand protocol do not have the ability to retransmit on error.
  4. Security – OSDP has built-in encryption options including AES128
  5. More features – OSDP provide means to add more elaborated capabilities such as controlling displays and files transfer for biometric and other smart devices.

Disadvantages of using OSDP

  1. Cost – OSDP compliant equipment and readers cost is higher than Weigand based products.
  2. Availability – Equipment and readers are not as common as Weigand products.
  3. Cost of Change – transition can be very expensive, requiring purchase of new hardware throughout the facility.
  4. Compatibility – even though OSDP is built with interoperability as a standard, it does allow some vendor specific variants. Unlike the fully transferable Weigand.


  1. Pricing – KEYKING price for OSDP readers is about the same as the Weigand version of the same model. DPU3000 controllers have OSDP at no additional cost
  2. Availability – Most of KEYKING readers are already available with OSDP version and are in-stock. Also, DPU3000 will work with other vendors OSDP readers as well
  3. Cost of change DPU3000 controllers allow mixing the technologies on the same hardware, so, only where needed, using OSDP and where not, keep the old Weigand readers.
  4. Compatibility – KEYKING had tested most of major manufacturers products and confirmed it’s compatibility. If compatibility issues arise, KEYKING R&D team is ready to resolve it, if needed.
  • David Dagan, VP Operations for America, is an active participant in the OSDP Committee since it’s inception.