Knowledge

The picture is normal but the dome camera is out of control. The problem most likely lies in the reverse data link. This article explains the role of the RS485 reverse channel in the video optical transceiver, the wiring steps with the decoder, and the troubleshooting ideas when the reverse channel is blocked.

The optical transceivers used for SD and HD surveillance are different. This article sorts out the key points of multi-channel video optical transceiver selection from three dimensions: signal format, channel number, and reverse data, to help integrators avoid wrong selections and missed selections before construction.

Disconnections at night, restarting as soon as infrared is turned on, and lags during peak periods are often confused. This article divides the characteristics of power supply and bandwidth according to three points: correlation with load, port status change, and packet loss location, and gives a list of records before reporting for repair.

When the site is moved, the network cable is lengthened. The device lights up but restarts when it is moved. The problem is often the power supply rather than the data. This article talks about the sources of voltage drop, three practical control lines, and the correct sequence of moving the photoelectric dividing point forward to solve long distances.

Port burning and repeated restarts during thunderstorms are mostly related to induction of lightning. This article explains why the photoelectric demarcation point can block the current inlet, the installation location of the two-level protection of the network cable and the power supply, the control value of the ground resistance and the key points of review after the thunder season.

There is a significant difference in power outage duration, construction cost and lightning protection difficulty between centralized power supply in the computer room and power extraction from nearby points. This article compares the two sets of architectures and provides three judgment methods and acceptance criteria based on regional mixing.

Park and factory surveillance often lead optical cables to poles, and then use network cables to connect to cameras. This article explains the three-stage division of labor of the hybrid link, the choice between placing the power supply on the pole side or the machine room side, and the method of marking the photoelectric demarcation point on the drawing.

PoE monitoring projects are often disconnected because the power account has not been settled. This article calculates based on three layers: the power standard is used to lock the upper limit of a single port, the peak value is calculated based on the infrared and gimbal startup current, and then the switch overall budget is used to select equipment in reverse and leave a margin.

This paper compares the fault tolerance differences among three industrial network topologies: chain, ring and dual-ring, explains how to infer the number of ring layers based on business concentration, the number of available optical fiber cores and the cost of line outage, and provides a two-step approach to the transformation project.

Explain the respective roles of the acquisition bus and transmission ring network, compare the three uplink methods of gateway conversion, serial port server and optical transceiver transparent transmission, and list three common pitfalls of terminal matching, ground loop and polling cycle.