Market Trends: OSDP improves reader communications

OnGuard release 5.12.110 introduced a new technology to the access control industry: the Open Supervised Device Protocol (OSDP), an open standard for communication between access control devices and their controllers.

The access control industry has made tremendous strides over the past 20 years, but one area that has remained essential unchanged is the way that readers are connected to access control systems. Early RFID readers popularized the Wiegand (D0/D1) interface, while magnetic stripe readers used an interface with Clock and Data signals. These two interface wiring schemes quickly became de facto standards for the access control industry, and they remain so today.

The two interfaces have a great deal in common. They are both point-to-point uni-directional protocols that utilize two wires plus a return wire to send a series of data bits from the reader to the system. Being point-to-point means that only one reader can be connected to an interface circuit. Being unidirectional, they provide no means for the system to send data to the reader, nor to request data from the reader. If data does need to be sent to the reader, additional discrete wiring is typically needed.

This unidirectional communication scheme has several drawbacks. Because the system is not able to request status from the reader, there is no easy way to determine the state of the reader other than by using additional circuitry or by simply waiting for a complaint from a user. Another drawback is that all device connection points must be continually ready to receive data in an unsolicited manner, frequently necessitating dedicated buffering circuits or high-speed parallel interrupt processing. Since there is no flow control capability, multidrop configurations are impractical due to the high risk of collisions and the impossibility of requesting a retransmission should a collision occur.

It has become increasingly clear that for reader technology and capabilities to progress, a bidirectional connection between the reader and access control system is a necessity. Some access control and reader manufacturers have recognized this need and developed proprietary bidirectional solutions. Lenel supports several of these, but the development and training investments made in proprietary solutions have no leverage.

From its inception, Lenel has been committed to open solutions that maximize end users’ and installers’ investments in hardware, software and training. Finding no satisfactory open solution for this specialized interface, Lenel, along with several key partners, undertook to develop a new open standard for reader–to-system communication. The OSDP protocol is the outcome of that effort, and has exceeded our expectations in terms of its ability to add significant capability while keeping costs under control.

The OSDP protocol provides bidirectional, supervised communication to and from readers and other devices, and does so using as few as two conductors plus shield (excluding reader power). Lenel’s current implementation of OSDP uses proven RS-422/RS-485 signaling levels to ensure reliable communication over the existing reader wiring infrastructure, while providing significant and tangible benefits in terms of reliability, functionality and performance.

By enabling bidirectional communication with readers, the Lenel hardware can continuously monitor the health of each reader without additional wiring or devices. Conditions such as reader failure, reader power supply failure, wiring damage, tamper or removal of the reader will be detected immediately and reported to the Alarm Monitoring application. This provides a significant improvement in situational awareness with respect to system readiness, and it does so with no additional configuration, wiring or licensing.

Reader supervision is in many cases a sufficient argument for substituting OSDP devices in place of devices that use legacy unidirectional interfaces. However, supervision is only a small part of OSDP’s value proposition. Allowing the access control system to transmit data to the reader device creates entirely new areas of possibility.

Instead of requiring separate wiring for user status indicators such as LEDs and sounders, the same wiring that sends card data to the system can be used to control user feedback at the reader. Because OSDP defines standard messaging for feedback, the behavior of heterogeneous readers connected to a common system can be homogenized, for a more consistent user experience across the enterprise.

While OSDP provides an efficient and effective tool for controlling binary indications such as LED ON/LED OFF and BUZZER ON/BUZZER OFF, it also opens the door to more flexible indication systems using alphanumeric displays and keypads. These types of human interface devices would be impractical to control remotely using legacy unidirectional interfaces. Devices that do offer them typically attempt autonomous state estimation and display from available signals, or rely on proprietary auxiliary communication paths that increase cost and/or complexity.

Lenel has tested our OSDP interface with prerelease versions of new readers that provide functionality fully equal to that available from the LNL-CK, which uses a proprietary RS-485 interface to control its LCD display and keypad. These new readers allow customized messaging from the system to the user, and also enable the keypad and display to provide intrusion keypad functionality combined with internal RFID card reader functionality.

After considering a variety of alternatives for promoting OSDP as a new industry standard, it was agreed that the best approach would be to offer it as a free and open standard. Any interested party can obtain an electronic copy of the OSDP documentation from Lenel and begin taking advantage of this significant step forward. Lenel has already provided the protocol to all of its key reader suppliers, and many of them will be offering OSDP readers before year end 2007. Lenel is also investigating the possibility of sanctioning OSDP as a true standard through one or more standards-making organizations.

The OSDP standard was designed to be flexible and scalable to meet the needs of a variety of applications both today and in the future. The standard defines methods for creating proprietary extensions that allow the capabilities of a specific device to be fully leveraged without interfering with the interoperability and ease of configuration and use that are intended to be the common denominator across all OSDP devices.

In the initial implementation of OSDP for our own products, we have made every effort to ensure a seamless transition from legacy interfaces to OSDP. The Lenel hardware and OnGuard software currently shipping will support either OSDP or legacy protocols on any reader port (except the port onboard the LNL-CK). The selection of OSDP, Wiegand, clock/data, or Bioscrypt RS-485 protocol is made on a port-by-port basis through the OnGuard software.

To reduce the need for new training, tools and system design techniques, the current implementation is strictly point-to-point, with one reader connected to one reader interface. Similarly, the wiring used and allowable distance of readers from reader interfaces (500 feet) remain unchanged for both legacy and OSDP protocols.

Because OSDP uses a bidirectional port instead of a unidirectional port on the reader interface module, the design of Lenel’s reader ports was changed in September 2006 to accommodate both OSDP and legacy protocols. Devices with these OSDP-compatible reader interfaces are referred to as Series 2 devices, and can be readily identified by the lack of a socketed memory chip on the circuit board. OSDP is supported by all Series 1 and Series 2 Intelligent System Controllers (ISCs) when used with OnGuard release 5.12.110 or later. For most systems, no controller upgrades are required beyond a simple firmware download. Lenel’s technical support, field sales or inside sales team can also assist in determining if an existing system supports OSDP and, if not, what upgrades to hardware, software or firmware might be needed to achieve compatibility.

Several Lenel customers are currently beta testing new OSDP readers. Expect further announcements from Lenel this summer as OSDP readers begin shipping.

With the release of the OSDP protocol, Lenel is attempting to move the industry forward, and Lenel resellers and customers will be in a leadership position in the deployment of systems that realize the many benefits of OSDP.

For more information on this topic, please contact: productmanagement@lenel.com