Compare the communication methods of the access controller
2025-05-29 02:07:44
[ Huaqiang Security Network News ] At present, the common communication methods of access controllers are RS-232, RS-485, and TCP/IP. Since the theoretical distance of RS-232 transmission is less than 15 meters, it is generally only used in small systems. This paper mainly discusses the application analysis of large-scale access control systems, focusing on RS-485 and TCP/IP networking methods. 
RS-485 communication method
The RS-485 communication method is multiple controllers. The RS-485 communication bus (must use twisted pair), the controller is connected in series, one bus is connected to the RS-485 converter (hub), and then connected. Go to the serial port of the computer to realize the management and communication of one computer to multiple controllers.
· Communication distance: The theoretical distance between the controller and the computer is 1200 meters;
· Number of loads: How many controllers can be carried by a 485 bus, depending on the selection of the communication chip of the controller and the communication chip of the 485 converter, generally 32, 64, 128, 256 Choice, this is the theoretical number. In actual application, it is affected by factors such as the on-site environment and communication distance, and the number of loads does not reach the number of indicators;
· Communication speed: The maximum transmission rate is 10Mb/s, and the length of the balanced twisted pair is inversely proportional to the transmission rate.
TCP/IP communication method
The TCP/IP communication method adopts the computer network universal standard protocol, and has the advantages of fast transmission speed, international standard, good compatibility, etc. The access mode is the same as that of the HUB and the computer network card of the local area network.
· Communication distance: In a small local area network, the communication distance of each level is up to 100 meters. The communication distance can be extended by HUB cascading, and even thousands of kilometers of networking can be realized across cities.
· Number of loads: There is no limit in theory, HUB can be cascaded;
· Communication speed: The communication speed is fast, ten or even dozens of times of RS-485/RS-232 controller; uploading permission or downloading hundreds of records per second.
Advantages and Disadvantages of RS-485 and TCP/IP Controllers Compared with RS-485 controllers, RS-485 controllers are inexpensive and can be networked separately without interference from the shared network of other devices. The disadvantage is that the number of networking is limited, generally less than 1000, the more devices are more interfered by the interference; at the same time, the network is limited in scope, the communication speed is relatively slow, and the uploading authority and downloading records are for large-scale access control systems with over 10,000 or over 100 doors. The operating speed is relatively slow. When it is necessary to increase the number of points, it is necessary to re-wire, which will incur additional costs (for example, decoration, etc.), and is not suitable for items that are distributed in different regions and need to be centrally managed.
The advantage of the TCP/IP controller is that it adopts the popular communication protocol of international standards, and the advancement and performance are relatively good. The number of networking is theoretically unlimited, the networking is wide, and the communication speed can be fast across regions and even across borders. Suitable for large access control systems; communication quality is stable and not susceptible to outside interference. If the user already has a local area network, the existing network can be used for networking. When adding a point, you can use the local area network that already exists, suitable for any system. The disadvantage is that the cost will be slightly higher than the RS-485 controller. If it is a large system, network management and network security will become new problems.
The RS-485 communication method is multiple controllers. The RS-485 communication bus (must use twisted pair), the controller is connected in series, one bus is connected to the RS-485 converter (hub), and then connected. Go to the serial port of the computer to realize the management and communication of one computer to multiple controllers.
· Communication distance: The theoretical distance between the controller and the computer is 1200 meters;
· Number of loads: How many controllers can be carried by a 485 bus, depending on the selection of the communication chip of the controller and the communication chip of the 485 converter, generally 32, 64, 128, 256 Choice, this is the theoretical number. In actual application, it is affected by factors such as the on-site environment and communication distance, and the number of loads does not reach the number of indicators;
· Communication speed: The maximum transmission rate is 10Mb/s, and the length of the balanced twisted pair is inversely proportional to the transmission rate.
TCP/IP communication method
The TCP/IP communication method adopts the computer network universal standard protocol, and has the advantages of fast transmission speed, international standard, good compatibility, etc. The access mode is the same as that of the HUB and the computer network card of the local area network.
· Communication distance: In a small local area network, the communication distance of each level is up to 100 meters. The communication distance can be extended by HUB cascading, and even thousands of kilometers of networking can be realized across cities.
· Number of loads: There is no limit in theory, HUB can be cascaded;
· Communication speed: The communication speed is fast, ten or even dozens of times of RS-485/RS-232 controller; uploading permission or downloading hundreds of records per second.
Advantages and Disadvantages of RS-485 and TCP/IP Controllers Compared with RS-485 controllers, RS-485 controllers are inexpensive and can be networked separately without interference from the shared network of other devices. The disadvantage is that the number of networking is limited, generally less than 1000, the more devices are more interfered by the interference; at the same time, the network is limited in scope, the communication speed is relatively slow, and the uploading authority and downloading records are for large-scale access control systems with over 10,000 or over 100 doors. The operating speed is relatively slow. When it is necessary to increase the number of points, it is necessary to re-wire, which will incur additional costs (for example, decoration, etc.), and is not suitable for items that are distributed in different regions and need to be centrally managed.
The advantage of the TCP/IP controller is that it adopts the popular communication protocol of international standards, and the advancement and performance are relatively good. The number of networking is theoretically unlimited, the networking is wide, and the communication speed can be fast across regions and even across borders. Suitable for large access control systems; communication quality is stable and not susceptible to outside interference. If the user already has a local area network, the existing network can be used for networking. When adding a point, you can use the local area network that already exists, suitable for any system. The disadvantage is that the cost will be slightly higher than the RS-485 controller. If it is a large system, network management and network security will become new problems.
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