Why can't the control line of the ball machine be controlled on the matrix but on the hard disk video recorder? The settings are the same.

How matrix and hard disk video recorder control ball machine at the same time

In the application of the existing monitoring system, the matrix host, the control keyboard host and the hard disk video recorder are generally stored separately in the monitoring system, but in many cases they need to be stored in the monitoring system. The matrix host is used for switching the screen curtain wall and the hard disk video recorder is used for video playback. In this case, in order to control the front-end ball machine, it is necessary to use a 485 * * player to share multiple 485 input ports into a 485 output port, and control the tripod head or high-speed ball through a unified 485 output port.

A, 485*** enjoy device to solve what problem?

In a residential property video monitoring project, the property management department needs two monitoring centers, the master and the slave, to check and control the Yuntai of the whole residential area. Moreover, each monitoring center is required to monitor the whole community through the matrix upper computer control platform, and the camera of the community is also required to record video through the hard disk video recorder. Therefore, it is necessary to require that multiple main control devices can coexist in a monitoring system.

During the construction, engineers found that if the matrix host and the hard disk video recorder were simply connected to a 485 bus, the whole monitoring system would be paralyzed due to the potential difference of each main control device and the signal reflection generated by the 485 bus, so engineers used the 485 bus * * * enjoyment device of Shenzhen Yu Electronics Co., Ltd. to complete this function. Connect the 485 wires of several main control devices to the input port of the 485*** enjoyment device, and enjoy the 485 output port through its * * *. Because the input port of the 485 * * exclusive device is electrically isolated, driven independently, and has a built-in high-performance CPU, it can effectively solve the problems of potential difference and signal reflection. So that a plurality of matrix hosts, hard disk video recorders and keyboard control hosts can be stored in a monitoring system.

Second, why do you need 485***

In industrial control, the common control bus mode is RS485 bus. Generally speaking, RS485 has three basic principles: 1, single transmission and multiple reception, 2, 32 receivers at most, 3, and the communication distance is about 1200m. In the usual industrial control, it is usually the control terminal, which just conforms to the first RS485 communication principle. RS485 communication mode is also the most commonly used in security monitoring system (the other is Manchester coding mode). There is usually only one control device, such as DVR (plug-in or embedded), matrix or ball keyboard (ball keyboard). But in some projects, there are many controlled devices (such as pan-tilt decoder, smart ball, etc. ), representative projects include residential quarters, road monitoring projects, traffic command center systems, etc. Such control devices are often not enough, so it may happen that both the matrix and DVR can control the front-end devices without affecting each other. In practice, some engineering installers try to connect DVR and other control devices in parallel with the control line of matrix to connect the control line of the front-end ball machine. But when you do this, you will find that it is often controllable for a while and uncontrollable for a while. This is actually not possible, and many practical cases have proved this! In addition, it is not feasible in theory. The most basic principle of RS485 communication mode is single sending and multiple receiving. "Single" means that there can only be one control device on the RS485 communication bus, that is, the master device. The above practice just violates this principle, and there are two or more master devices (both matrix and DVR are master devices). Therefore, a device is needed to solve the problem of simultaneous control of multiple main devices, and the 485*** enjoyment device came into being. The 485*** enjoyment device coordinates the main equipment through the built-in high-performance central processor, and then sends it out through the RS485 control bus according to a certain strategy. 485*** enjoyment device has priority function, which can realize different control rights of different devices!