Common communication and networking methods of access control controllers

The common communication methods of Access Control controller are: RS232 RS485 TCP/IP method.

1. RS232 method:

It means that a single controller is connected to a computer serial port through the RS232 serial port communication protocol for point-to-point management.

RS232 is also called serial communication by some people.

RS232 communication mode, the farthest communication distance is 13 meters (the communication is stable within this distance), and the most stable within 3 meters. Although the test above 13 meters seems to be able to communicate, but it is unstable and has poor anti-interference ability. It is not recommended to do so. A general desktop computer has 1-2 serial ports (Com1 Com2), which can be expanded to a maximum of 255 serial ports through a multi-serial port card. New notebooks generally do not have serial ports, and you need to purchase a USB serial converter to achieve this. RS232 Each serial port can only communicate with one controller.

2. RS485 communication method:

Multiple controllers, through the RS485 communication bus (must use twisted pair, or one of the network cables), connect the controllers in series by hand in hand, one bus is connected to the RS485 converter (hub), and then connected to On the computer serial port, realize the management and communication of one computer (software) to multiple controllers.

Communication distance:

The theoretical distance between the farthest controller and the computer is 1200 meters. It is recommended that the customer control it within 800 meters, and the best effect can be controlled within 300 meters. If the distance is too long, you can purchase a 485 repeater (extender) (please buy it from a professional converter manufacturer. Whether the repeater is placed in the middle of the bus or at the beginning, please refer to the instructions of the relevant manufacturers.) The repeater can theoretically be extended to 3000 meters.

Number of loads:

That is, how many controllers a 485 bus can carry depends on the selection of the communication chip of the controller and the communication chip of the 485 converter. Generally, there are 32, 64, 128, and 256 options. This is a theoretical In actual application, according to factors such as site environment, communication distance, etc., the number of loads cannot reach the target number.

3. TCP/IP communication method:

The TCP/IP communication protocol is a common standard protocol for current computer networks, with the advantages of fast transmission speed, international standards, and good compatibility.

The access method of the controller is the same as the access method of the HUB of the local area network and the computer network card.

Communication distance:

In a small local area network, the communication distance can be extended by cascading the HUB. The communication distance of each level can reach 100 meters, and multiple levels can be cascaded. Moreover, in large-scale local area networks, it can be extended to a long distance or even several kilometers through various methods such as optical fiber and wireless, and even across cities, it can also be connected to thousands of kilometers through the Internet.
Number of loads:

There is no limit in theory, HUBs can be cascaded, and there is no problem in networking with thousands of controllers.

Communication speed:

The communication speed is fast, and the communication speed of the TCP/IP product is ten times or even dozens of times that of the RS485 RS232 controller. There are more than 100 or even hundreds of upload permissions or download records per second.

4. Other communication networking methods:

In addition to the mainstream communication methods of RS485 TCP/IP, a very small number of companies also use LAN LONGWORK and other bus methods for networking. These methods are rarely used and have advantages and disadvantages. The interchangeability between products is not good, and the technology is not Popularity, not introduced here.

Most RS485 access control controllers have RS232 communication ports, but generally need to use jumper or DIP switch to set which communication method is used.

Some brands of controllers integrate RS485 and TCP together, and are designed with dual communication methods. This design cost is relatively high and the practicability is not strong. It is mainly common in some imported brand products.