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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. The connection method of the 120Ω matching resistance of the dome terminal is as follows: The 120Ω matching resistance of the dome terminal can be connected by the dial switch on the chassis of the dome. With Modbus, BACnet and Profibus, A/B labeling refers A as the negative green wire and B as the positive red wire, in the definition of the D-sub connector and M12 circular connector, as can be seen in Profibus guides. For an off, mark or logic 1 state, the driver's A terminal is negative relative to the B terminal. The issue also exists in programmable logic controller applications. In a computer system, SCSI-2 and SCSI-3 may use this specification to implement the physical layer for data transmission between a controller and a disk drive. The two values provide a sufficient margin for a reliable data transmission even under severe signal degradation across the cable and connectors. 2. Ordinary twisted pair shielded cable STP-120Ω (for RS485 & CAN) one pair 18 AWG, the cable outer diameter is about 8.2mm. Suitable for indoor, pipeline and general industrial environment.

1. Ordinary network cables have no shielding layer and cannot prevent common mode interference. Cable jacket: Made from high-quality PVC, the outermost jacket layer has high elasticity, helping to protect the cable from strong environmental impacts. When in use, it is recommended that both ends of the armor layer be grounded and the innermost shielding end is grounded. End of line termination resistor (120 ohm 1/4 watt) to be installed at both ends of network. If one or the other end fail to see the heartbeat packets come or get acknowledgement of them then know that your cable is either disconnected or has broken wires. The equipment located along a set of RS-485 wires are interchangeably called nodes, stations or devices. Devices (Device 1, Device 2, Device N) are connected in series, forming a daisy chain topology. How many devices can be connected to a bus? RS-485 and RS-422 can interoperate with certain restrictions.

The EIA has officially disbanded and the standard is now maintained by the TIA as TIA-485, but engineers and applications guides continue to use the RS-485 designation. The standard does not discuss cable shielding but makes some recommendations on preferred methods of interconnecting the signal reference common and equipment case grounds. In fact, there is no such thing as an RS485 cable since RS485 is a protocol for serial communication (like between inverter and Zero export device) and Ethernet is a protocol for carrying internet data (between router and inverter) whereas CAT6 is a cable standard. RS-485, like RS-422, can be made full-duplex by using four wires. A typical mistake is to connect two nodes with only two wires. I thought that the whole idea was that the 2 data wires carried a differential voltage. RS-485 supports inexpensive local networks and multidrop communications links, using the same differential signaling over twisted pair as RS-422. B line (or Data-), handles the complementary differential signals. The truth tables of most popular devices, starting with the SN75176, show the output signals inverted. The specifications of the shielded twisted pair used are related to the distance of the 485 communication line and the number of connected devices, as shown in the following table.

An RS485 cable can carry data upto 4000ft (or 1.2km) @ 100kbps as shown below. As shown below. When the dome camera leaves the factory, what is rs485 cable the 120Ω matching resistance is not connected by default. Finally check the documentation on your RS485 device to see how to set it up, and if can be disabled by default. You can connect the 120Ω matching resistance to the line by turning the 10th bit of the DIP switch to ON. The diagram below shows potentials of the A (blue) and B (red) pins of an RS-485 line during transmission of one byte (0xD3, least significant bit first) of data using an asynchronous start-stop method. Control and monitoring systems: A single pair of rs485 signal cable can connect up to 32 devices, with a signal transmission distance of up to 1200m. Therefore, using rs485 cables is an ideal choice for industrial control and monitoring systems, especially those with large-scale and high dispersion.