These 10 Hacks Will Make You(r) Rs485 Cable (Look) Like A professional > 자유게시판

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Using a repeater, the main cable is divided into different segments, each of which can be up to 700 m in length and connect 32 devices (this number includes the repeaters). The main cable must be no longer than 700 m! The DIP16 connector on the ribbon cable plugs directly into the breadboard. All headers are on a 0.1" grid to allow accessory proto-boards to span multiple connectors if needed. The power input connector can be a coaxial barrel connector, a 2-pin terminal block, or a MTA-100 connector or 0.1" spacing header. The cabling of the industrial communication systems (Modbus RS485) is different in some ways from the cabling used for power cabling and the electrician may experience some difficulties if he is not an expert in Modbus communication networks. Henceforth, we shall consider Slave devices to be measuring instruments with serial communication, even if the cabling is similar for all Modbus devices. This makes it easier to identify cabling errors.

In order to avoid errors when many devices are connected, cables of the same colour should be used for all the connections to the terminals A and cables of the same colour should be used for all the connections to the terminals B of the various devices (e.g. white for A and blue for B). All the ‘A’ terminals must be connected together and all the ‘B’ terminals must be connected together respectively. In order to avoid signal reflections, a 120 Ohm termination resistance must be fitted on each end of the main cable. 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. If on the other hand each terminal can accept only a single cable, a proper branch must be created using three auxiliary terminals for each instrument to be connected.

Users can utilize a longer cable, up to 1200 meters or 4000 feet. The branches must be no longer than 1200 m! The end resistance must be used only at the ends of the main cable. This distance does not include the branches (which must nevertheless be short). The RS485 system used for Modbus communication provides a main cable (Bus or backbone), to which all the devices have to be connected with branches (also known as stubs) that are as short as possible. This allows either twisted pair cables to be used with terminal blocks, or Ethernet Cat5e or Cat6e cable to be used with RJ45 jacks. You can also still simply use a terminal strip. Although not nearly as widely used today, they can still be found in some areas. Serial data communications standards - RS-232, RS-422, & RS-485 were widely used for data transfer providing easy connectivity for the time and they can still be found today. RS232 could only handle one at a time. Access control systems: Rs485 cables are mainly used to connect and transmit data between access control devices such as security gates, RFID cards, or time attendance machines and the control center. Rs485 cables not only vary in the structure of the core but also in the number of twisted pairs.

All in all, RS485 really allowed full automation possible with its ability to connect so many devices at once. In this case it is possible to connect the main inlet and outlet terminal directly to the terminals of an instrument without creating a branch. Various build options are possible including 4-wire serial, 1x10-pin female ComBoard header, or a 2x5-pin shrouded header for use with ribbon cables. In some countries, inserting two cables into the same screw terminal is permitted. Serial data transmission links used cables with a variety of different functions to enable data to be sent reliably between two equipments. The shielding may be braided (be formed by a mesh of thin conducting wires) or be a foil (consisting of a sheet of metal wound around the conductors): the two types are equivalent. Each device has a communication port with two terminals, which are indicated for the sake of convenience as A and B. In these two terminals the communication cable is connected so that all the devices that take part in the communication are connected in parallel. A DIL16-to-DIP16 ribbon cable can be used to carry the signals, power, and ground to a breadboard. The greatest feature of RS485 is the fact that you can connect up to 32 devices on one system.

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