RS485 interface: Transmission difference signal logic "1" is expressed as + (2-6) V between two lines Logic "0" is represented by the voltage difference between the two lines as - (2-6) V.If the level of the interface signal is lower than rS-232, it is not easy to damage the chip of the interface circuit, and the level is compatible with TTL level, so it is convenient to connect with TTL circuit.Ī. In addition, the anti-interference ability is poor.ī. It is easy to damage the chip of the interface circuit because it is related to TTL level (0~ "& LT 0.8 v, 1 ~ "& gt 2.0V ") is not compatible, so level conversion circuit is needed to connect with TTL circuit. RS232 interface: the signal level of the transmission level signal interface is relatively high (signal "1" is "-3V to -15V", signal "0" is "3-15V"). What is the difference between RS232 and RS485 communication interface?Ī. The RS485 interface connector USES DB-9's 9-core socket, the RS485 interface with the intelligent terminal USES DB-9 (hole), and the keyboard interface RS485 USES DB-9 (pin). In many cases, connecting the RS-485 communication link is simply A pair of twisted pairs connecting the "A" and "B" terminals of each interface. The RS485 communication network is generally adopted in the master-slave communication mode, that is, a host with multiple slaves. The connection mode is bus-type topology, and 32 nodes can be connected on the same bus at most. RS485 interface composed of the half-duplex network is generally two-wire system (there was a four-wire connection method, can only achieve point-to-point communication mode, now rarely used), the use of shielded twisted pair transmission. RS485 without specific physical shape, according to the actual situation of the project and the use of the interface.
#RS485 CONNECTOR PC#
Some devices connect to the RS-232 interface of the PC because they do not use the transmission control signal of the other side, they only need three interface lines, namely "send data", "receive data" and "signal ground".Therefore, the 9-core plug seat of DB-9 is adopted, and the transmission line is a shielded twisted pair. The connector shall be a 25-core plug holder model DB-25. So the RS232 interface is now called DB9. Instead of db9, the pins used in DB9 are different from db25, namely 2 (RDX), 3 (TXD), and 5 (GND). With the continuous improvement of the equipment, db25 pins are rarely seen now.
#RS485 CONNECTOR SERIAL#
Generally, only 2 (RDX), 3 (TXD), and 7 (GND) pins are used in the serial port of DB25. The signal content of each pin of the connector is specified, as are the levels of various signals. The standard specifies a 25-pin DB25 connector.
#RS485 CONNECTOR FULL#
Its full name is the Technical Standard for Serial Binary Data Interchange Interface between Data Terminal Devices (DTE) and Data Communications Devices (DCE). Electronics Industry Association (EIA) in conjunction with Bell systems, modem manufacturers, and computer terminal manufacturers. Rs232 interface is a standard for serial communication developed in 1970 by the U.S. There are two groups of RS-232 interfaces on personal computers, which are called COM1 and COM2 respectively. One of the computer communication interfaces, the RS-232 interface usually comes in the form of 9 pins (DB-9) or 25 pins (DB-25). The physical structure of the RS232 interface and RS485 interface RS232 and RS485 is a common weak current interface, to understand what is the difference between RS232 and RS485 today.
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