Brief analysis of the requirements of security cables in the access control system

In recent years, science and technology have made rapid progress, and the information industry has also been vigorously developed, and wire and cable is the blood vessel of industry, so the demand for wire and cable products is also increasing
.
In fact, new wire and cable products have indeed sprung up, showing their skills in various emerging high-tech industries, such as communication cables, security cables, fire cables, etc
.

It is reported that the annual growth rate of the cable market is about 8%-12%, of which the growth rate of security cables is particularly eye-catching, although China's security cable industry has some problems, such as late start, backward technical equipment, etc.
, but its growth rate can be maintained between
15% and 20% per year.
After more than 30 years of vigorous development, China's security industry has more and more industry segments, and the application range is increasing, among which the security cable in the access control system is also a part
that cannot be ignored.

In the building video intercom system, the quality requirements for the connection cable are quite high
.
The cable transmitting voice signal and alarm signal is mainly using more than 4 cores of polyvinyl chloride sheathed flexible wire (RVV), and the video transmission is mainly coaxial SYV-75-5, and now there are also some new technologies for signal transmission including video transmission with network-to-twisted wire, and no coaxial cable
is used.
If the system is to prevent external interference or cannot be grounded, the connection wire used in the system must be shielded cable such as shielded wire (RVVP
).

RS-232-C is a serial physical interface standard
developed by the Electronic Industry Association (EIA).
rs is the abbreviation of the English "Recommended Standard", 232 is the identification number, and C represents the number of modifications
.
The RS-232-C bus standard has 25 signal lines, including a main channel and an auxiliary channel, in most cases the main channel is used, for general duplex communication, only a few signal lines can be implemented, such as a transmit line, a receive line and a ground wire
.
The RS-232-C standard specifies data transmission rates of 50, 75, 100, 150, 300, 600, 1200, 2400, 4800, 9600, 19200 baud
per second.
The RS-232-C standard stipulates that the driver is allowed to have a capacitive load of 2500PF, and the communication distance will be limited by this capacitance, for example, when using a 150PF/m communication cable, the maximum communication distance is 15m; If the capacitance per meter of cable decreases, the communication distance can be increased
.
Another reason for the short transmission distance is that RS-232 is a single-ended signal transmission, which has problems such as common ground noise and cannot suppress common-mode interference, so it is generally used for communication
within 20m.

With the rapid development of China's national economy and information technology, foreign-funded enterprises look at China's huge cable market and continue to pour into the country, coupled with the increasing attention of the domestic people to security, I believe that domestic security cables will usher in a peak period of development
.