Ordinary twisted-pair cables can be used in general occasions, and shielded coaxial cables can be used in environments with relatively high requirements. 1. Ordinary network cables have no shielding layer and cannot prevent common mode interference. The method to eliminate differential mode interference is to add a bias resistor (matching resistance in the dome camera) to the circuit, and use twisted-pair wires; common mode interference is transmitted between the signal line and the ground, which is asymmetrical interference. As shown below. When the dome camera leaves the factory, the 120Ω matching resistance is not connected by default. It is best to connect a 120Ω terminal resistor at both ends of the RS485 device. Some of these converters can convert from RS232 to both RS485 and RS422 however many standard models only has one of the protocols. A RS232 - RS422 converter is a 4-wire, full-duplex, differential protocol with multi-drop capabilities and a recommended distance limit of 4000ft. ANSI/TIA/EIA-422-B is the American national standard for the RS422 protocol.

The RS232 - RS422 converter is also often used in older serial devices such as older PLC's and terminal equipment. In most cases, RS485-based devices can employ communication protocols such as Modbus and ASCII to establish communication with a central control system. The Serial PPP View visualizer can be used to decode Point-to-Point Protocol packets, as well as a number of packets that can be encapsulated in PPP packets.PPP View supports the following protocols: Novell IPX, OSI Network Layer Control Protocol, DECnet Phase IV Control Protocol, Appletalk Control Protocol, Link Control Protocol, Password Authentication Protocol, Link Quality Report, Challenge Handshake Authentication Protocol, Multilink Protocol, Compression Control Protocol, Extensible Authentication Protocol, what is rs485 cable NETBIOS Protocol. Carry a few converters with you so that you can rule out whether the quality of the converter is affecting the communication quality. The longer the communication distance, the higher the baud rate, the thinner the wire diameter, the worse the wire quality, the worse the quality of the converter, and the insufficient power supply of the converter (passive Converter), the stronger the lightning protection, these will reduce the real load quantity.

The list is automatically updated every time you plug or unplug a serial device.Each device's communications can be monitored in real time, and highly efficient and carefully optimized data processing algorithms help avoid communication delays. All operational algorithms are carefully optimized in order to get the maximum performance, so the real-time solutions based on this product can be appropriate even where any other solution will not give proper results. The star structure will produce reflected signals, which will affect the 485 communication. It should be judged according to the model of the chip in the 485 converter and the model of the 485 device chip, and the load capacity can only be determined according to the chip with a lower index. If there are many load 485 devices, the wire impedance is not up to the standard, the wire diameter is too thin, the converter quality is poor, the equipment lightning protection is complicated, and the baud rate is increased. The condition is that the communication wire is high-quality and meets the standard, the baud rate is 9600, and only one 485 device is loaded, so that the communication distance can reach 1200 meters, so the actual and stable communication distance of the 485 bus is usually less than 1200 meters.

These manufacturers all agree on the meaning of the standard, and their practice is in widespread use. Category 5 (Cat 5, Cat 5e, and Cat 6) cables are the most common Ethernet cables in use today. The use of shielded twisted-pair cables helps to reduce and eliminate the distributed capacitance between the two 485 communication lines and the common mode interference generated around the communication lines. Be sure to use a wire pair such as the blue and blue/white pair for the data lines and a third wire or pair twisted together for the common connection. Differential mode interference is transmitted between two signal lines and belongs to symmetrical interference. The 485 communication line is composed of two twisted-pair lines. Only when the 485 communication distance exceeds 300 meters, the terminal resistance should be added at the beginning and end of the 485 communication. If long-distance transmission is really needed, optical fiber can be used as the propagation medium, and a photoelectric converter is added at both ends of the transceiver.