Design Recommendations: Difference between revisions
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== Protocols== | |||
This page outlines our recommendations for open-source access control product standards. Specifically, we address physical and electrical interfaces. | This page outlines our recommendations for open-source access control product standards. Specifically, we address physical and electrical interfaces. | ||
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====Bi-Directional Protocol Standards==== | ====Bi-Directional Protocol Standards==== | ||
*Peripheral nodes such as door readers, sensor boards and keypads should support RS-485 or CAN bus. The advantages of CAN bus include support for message prioritization, a larger address space and support for more nodes, while RS-485 is simpler and many commercial devices already support it. | |||
*Point-to-point serial over USB or RS-232 is acceptable for interface to a monitoring/control computer. Modern PCs have limited options for I/O, so any device that does not support Ethernet will most likely communicate with the PC either through an intermediate node or a serial USB/RS-232 connection. | |||
*Controller nodes that have sufficient resources to run an IP stack should be connected via Ethernet, especially if a client/server authentication model is planned. | |||
*For alerting and monitoring connections to the outside world, IP connectivity is going to have the fastest data rate and message delivery time of the above methods. A data-capable cellular device (GSM card or smartphone SDK interface) is an option for areas that lack connectivity or as a backup. POTS service via a serial modem is simple and robust, but lacking in functionality. | |||
===Physical Standards=== | ===Physical Standards=== | ||
Latest revision as of 11:36, 21 October 2011
Protocols
This page outlines our recommendations for open-source access control product standards. Specifically, we address physical and electrical interfaces.
Signalling Standards
- All new open-source access and security hardware should support legacy protocols such as Wiegand or clock-and-data as needed, due to the variety of devices available on the market.
- All newly developed panels or peripherals should support a bi-directional protocol.
Bi-Directional Protocol Standards
- Peripheral nodes such as door readers, sensor boards and keypads should support RS-485 or CAN bus. The advantages of CAN bus include support for message prioritization, a larger address space and support for more nodes, while RS-485 is simpler and many commercial devices already support it.
- Point-to-point serial over USB or RS-232 is acceptable for interface to a monitoring/control computer. Modern PCs have limited options for I/O, so any device that does not support Ethernet will most likely communicate with the PC either through an intermediate node or a serial USB/RS-232 connection.
- Controller nodes that have sufficient resources to run an IP stack should be connected via Ethernet, especially if a client/server authentication model is planned.
- For alerting and monitoring connections to the outside world, IP connectivity is going to have the fastest data rate and message delivery time of the above methods. A data-capable cellular device (GSM card or smartphone SDK interface) is an option for areas that lack connectivity or as a backup. POTS service via a serial modem is simple and robust, but lacking in functionality.
Physical Standards
- Standard RJ-45 connectors for all wired Ethernet applications
- Removable 3.5mm screw terminals for other hard-wired connections up to 5A
- Fixed or removable 5mm screw terminals for higher current power connections
- Anderson Power Pole connectors for battery and high-current DC power supply connections