Weigand

The Weigand protocol uses a series of pulses to transfer data between a card reader and a control panel. The data is encoded in the width of the pulses, with a specific number of pulses indicating a binary "1" and a different number of pulses indicating a binary "0". The data is usually encoded in a 26- or 34-bit format, depending on the specific application.

One of the key advantages of the Weigand protocol is that it is relatively simple and easy to implement. It also has a relatively low data rate, which makes it less susceptible to interference or errors caused by electromagnetic interference (EMI). Additionally, Weigand protocol is widely supported by most card readers and control panels available on the market, making it a popular choice for many access control systems.

However, the Weigand protocol has some limitations. One of the main limitations is that it is not very secure as it does not include any encryption or authentication mechanism. This makes it vulnerable to replay attacks, where an attacker intercepts the data sent between the card reader and the control panel and then replays it to gain unauthorized access.

In recent years, newer and more secure protocols such as Wiegand26 with Facility Code, OSDP and Mifare have been developed to replace the Weigand protocol in some cases, but it is still widely used in many access control systems.

It's important to keep in mind that the protocol used in an access control system should be chosen based on the specific needs and security requirements of the application. It's also important to regularly update the firmware and software of your access control system to ensure that it remains up to date and secure.