Key takeaways
- OSDP is a standard for the link between a reader and its controller. It is published by the Security Industry Association (SIA) and as the international standard IEC 60839-11-5.
- Encryption comes from Secure Channel, OSDP's encrypted mode, which has to be set up. A system can run OSDP without it.
- Both the readers and the controller have to support OSDP, the cable has to suit it, and someone has to set addresses and keys.
- "Supports OSDP" is a maker's own claim. "OSDP Verified" means the product passed third-party testing under SIA's program.
First distinction
What OSDP covers, and what it doesn't
The reader on the wall reads the card and passes its number to the controller, usually in an equipment room. OSDP is the set of rules for that conversation.
SIA adopted OSDP in 2012. It was approved as an international standard in May 2020, and SIA's v2.2.2 was released in October 2024. Readers for fobs, smart cards, phones and keypads can all use it. For where the reader and controller sit among the other parts, see how commercial access control works. For the card side, see prox cards vs. smart cards.
| Part of the system | Does OSDP cover it? | What that means for you |
|---|---|---|
| The cable between reader and controller | Yes. This is what OSDP is | Two-way messages, a check on the reader, and encryption once it is set up |
| The card or fob | No | A card that is easy to copy stays easy to copy. The card technology decides that |
| Whether the link is encrypted | Only when the encrypted mode, called Secure Channel, has been set up | "OSDP readers" on a quote says the readers can use it, not that encryption will be on |
What it changes
OSDP compared with the older interface, Wiegand
Many existing readers use an older one-way interface called Wiegand. Which one a door needs depends on the door.
The two-way link is also what can let settings and reader software updates be sent from the controller, where both ends support that feature. For the older interface and the card formats that go with it, see what is Wiegand.
| What differs | Wiegand | OSDP |
|---|---|---|
| Direction | One way, from the reader to the controller | Two way. The controller can also send messages to the reader |
| Encryption | None. The card data is sent unencrypted | Can be encrypted with AES-128, a widely used encryption standard, once Secure Channel is set up |
| Checking on the reader (called supervision) | The controller has no way on this link to confirm the reader's status | The connection is supervised, so a reader that stops responding can be reported |
| Wiring | Ordinary reader cable, which was not chosen with OSDP in mind | A different kind of cable connection, called RS-485. Several readers can share one run of cable (called multi-drop) |
The encrypted mode
What Secure Channel is, and why to ask about it
Secure Channel is OSDP's protected mode. It encrypts the data passing between the reader and the controller, so someone who reaches the cable sees scrambled data instead of card numbers.
It has to be set up. The reader and the controller are paired with a shared key, a secret value that both ends hold, and each end then uses it to prove itself to the other and to encrypt the link. That pairing is done when the system is commissioned, which means set up and tested door by door.
OSDP also runs without it. In its basic mode the link is still two-way and still supervised, but the data is not encrypted. SIA's installation guidance is that the unsecured mode should exist only during initial setup, before Secure Channel is established.
Keys need looking after. A replacement reader has to be paired before it works on an encrypted link, and whoever does that needs to know how the keys are set and where they are recorded.
What it takes
What OSDP needs to work
OSDP is not a setting on the reader alone. Four things have to line up, and the fifth is the work of setting them up.
Readers that support it
Some readers can be set to either Wiegand or OSDP, and some support only one. The reader's data sheet says which.
A controller that supports it
The controller has to speak OSDP too, and support the features you want from it, such as several readers on one run and remote management, and the number of readers planned for each connection. Ask whether it supports Secure Channel.
Suitable cable
For a new installation, SIA's guidance is cable rated for RS-485. This is normally shielded twisted-pair cable, in which the data wires are twisted together to resist electrical interference.
A sensible layout
Where several readers share one run, they are normally wired one after another along a single line, not branching out from a central point. How many readers can share a run, and how long it can be, depends on the controller, the readers and the cable, and their installation guides set those limits.
An address for each reader, and commissioning
Each reader on a run needs its own address, a number the controller uses to tell readers apart. Someone has to set the addresses, pair the keys, test each door and write down what was set.
Reading a data sheet
"Supports OSDP" and "OSDP Verified"
SIA runs a testing program called OSDP Verified. A product that carries the mark has been tested by a third-party lab against the OSDP standard and its performance profiles, which are defined sets of features. Verified products appear on SIA's OSDP Verified Product List.
A maker can describe a product as "supports OSDP" or "OSDP compliant" without that testing. Those words are the maker's own claim. They don't mean the product is faulty, and they don't mean it has been independently checked.
The mark tells you the product itself passed the tests. It doesn't tell you how your system was set up: whether Secure Channel is on, how keys are kept, or whether the cable was tested. For a controller, SIA's guidance is to check that the software version on it is the one that was verified.
Changing over
Moving from Wiegand to OSDP
A changeover does not have to happen at every door at once. These are the points to raise with the installer.
- The controller and any converter. Whether your controller accepts both kinds of reader at once, or needs a converter between old and new, decides whether doors can change one at a time.
- The readers. Readers that support both can sometimes be switched over in place. Others are replaced.
- The cable. Existing cable can often be reused, but not in every building, because older reader cable was not chosen with RS-485 in mind. Ask the installer to test it with a cable tester before anyone promises that it will carry over.
Your building
How to tell what you have, and what to ask
You can't tell from the front of a reader, because many readers can be set up either way. Leave the reader on the wall and the controller cabinet closed: both carry power, and pulling a reader can set off a tamper alarm.
- Ask the technician to show you, in the controller's settings, whether each reader is set to OSDP.
- Ask the same for Secure Channel, door by door. A quote or the as-built drawings (the record of what was installed) will list the readers' part numbers, which lead to data sheets, but they will not show whether Secure Channel is on.
| Your situation | What it points to | What to ask |
|---|---|---|
| A quote lists "OSDP readers" | The readers can use OSDP. The quote may not say how they will be connected | Will they be wired and set up as OSDP, on which controller, and with Secure Channel on? |
| You were told new readers "should be OSDP" | Something to confirm when buying. What it involves depends on your controller and cable | Does our controller support OSDP and Secure Channel, and what changes at each door? |
| Your system runs on Wiegand and works | OSDP and Wiegand work differently, and which one suits a door depends on the readers, the controller and the cable | Would our current readers and controller support OSDP if we change later? |
| Your system already runs OSDP | The link is two-way. Whether it is encrypted depends on how it was set up | Is Secure Channel on at every door, and can you show me? |
| You are moving to cards that are harder to copy | The card and the cable are separate questions | How does the card data travel from the reader to the controller, and is that link encrypted? |
- How are the keys set, who keeps the record, and does it stay with the building?
- Are the readers and the controller OSDP Verified, and on which software version?
- What happens when a reader is replaced: who sets its address and pairs it?
- Was the existing cable tested for OSDP, and what did the test show?
If you want a second look at your readers
Elwin Security installs, repairs and supports card reader and key fob access control for commercial and multifamily properties, Santa Clara-based and serving the San Francisco Bay Area. Calls are answered 8:00 AM-8:00 PM daily at (408) 539-0535.
Common questions
OSDP questions
What does OSDP stand for?
OSDP stands for Open Supervised Device Protocol. "Supervised" refers to the controller being able to check on the reader over the two-way link.
Is OSDP encrypted?
Only when Secure Channel, its encrypted mode, has been set up. Without it, OSDP runs in a basic mode that is not encrypted, so ask which one your doors use.
What is the difference between OSDP and Wiegand?
Wiegand sends card data one way and unencrypted. OSDP is two-way, lets the controller check on the reader, and can encrypt the link once Secure Channel is set up.
Does OSDP stop cards from being copied?
No. OSDP covers the cable between the reader and the controller. Whether a card or fob can be copied depends on the card technology, which is chosen separately.
Do I need a new controller for OSDP?
Only if the current one doesn't support OSDP. Ask the installer whether yours does, and whether it supports Secure Channel as well.
Sources and further reading
These sources back up the general guidance. Your building and the people who approve the work decide the details for your doors.
- Security Industry Association: Open Supervised Device Protocol (OSDP) (archived copy)
- Security Industry Association: SIA OSDP Verified (archived copy)
- Security Industry Association: Implementing OSDP Access Control? Follow This Simple Checklist, February 2026 (archived copy)
- Security Industry Association: There Is a Hole in the Boat: Why Access Control Professionals Need to Move From Wiegand to OSDP, 2021 (archived copy)
- International Electrotechnical Commission: IEC 60839-11-5:2020, Open supervised device protocol (OSDP)