The Hidden Thriller Behind Rs485 Cable > 자유게시판

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The RS232 signals are represented by voltage levels with respect to a system common (power / logic ground). The data is coded as a differential voltage between the wires. Especially when the transmission is carried over a long wire outdoor, the wires is potential to carry the dangerous signal like lightning or other high voltage induction. The recommended arrangement of the wires is as a connected series of point-to-point nodes, a line or bus. Since it uses a differential line over twisted pair (like EIA-422), it can span relatively large distances (up to 4000 feet or just over 1200 metres). Extending a RS232 line is done by converting the RS232 signal into RS422 and then back to RS232 at the remote end. RS422 (differential) was designed for greater distances and higher Baud rates than RS232. In its simplest form, a pair of converters from RS232 to RS422 (and back again) can be used to form an "RS232 extension cord." Data rates of up to 100K bits / second and distances up to 4000 Ft. As it is a half-duplex IC hence it can not both transmit and receive at the same time.

It provides a convenient means of connecting the QScreen Controller to a variety of peripheral devices, including analog to digital and digital to analog converters, real time clocks, rs485 cable and other computers which use high speed communication. I tried connecting it directly to the computer either with a normal network cable or with a crossover cable but the web page doesn't open. While a multi-drop "type" application has many desirable advantages, RS422 devices cannot be used to construct a truly multi-point network. RS422. RS422 is also specified for multi-drop (party-line) applications where only one driver is connected to, and transmits on, a "bus" of up to 10 receivers. The RS232 - RS422 converter is also often used in older serial devices such as older PLC's and terminal equipment. Since both channels can operate simultaneously and independently, serial debugging can be performed while the application program is communicating via its primary channel.

In general if you are not connected to a modem the handshaking lines can present a lot of problems if not disabled in software or accounted for in the hardware (loop-back or pulled-up). RS232 has numerous handshaking lines (primarily used with modems), and also specifies a communications protocol. It does not specify or recommend any communications protocol; Other standards define the protocols for communication over an RS-485 link. The communication is based on Modbus TCP converters to Satchwell ™ MN300, MN440, MN500, MN620 (485 NCP protocol) type I-7188E2-S-NCP. The RS232 protocol provides for four handshaking signals called ready to send (RTS), clear to send (CTS), data set ready (DSR), and data terminal ready (DTR) to coordinate the transfer of information. 12 volts and outputs logic level (0 or 5 volt) signals to the UART circuitry. Differential signals can help nullify the effects of ground shifts and induced noise signals that can appear as common mode voltages on a network.

The complete working of this project can be found in the video linked below. When the exchange is complete, the slave can again execute the Silence() routine to disable its transmitter and begin listening for its name. The hardware detects the start-bit of the transmission and automatically enables (on the fly) the RS485 transmitter. RS485, also known as TIA/EIA-485 is a standard serial communications protocol defining the electrical characteristics of a serial converter, drivers and receivers for use in balanced RS485 digital multipoint systems. Although the maximum standard baud rate of the primary serial port is 19200 baud, nonstandard baud rates of over 80 Kbaud can be attained by the 68HC11's on-chip UART and the onboard RS232 driver. Maximum Cable Length 50 FT. This 6 ft long cable comes with a USB connector on one end and the red and yellow tipped plugs and does not require a driver if used with Windows 7 or later versions.