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The point-to-point full-duplex RS-485 network allows you to get the complete prototype system fully operational quickly, since it is easier to debug and more immune to certain common problems on other systems (noise problems on RS-232, turn-around problems on half-duplex RS-485, etc.). Half-Duplex RS-232 is usually limited by an additional communications device between the two farthest ends that are communicating. 2, and this pin is defined as "Transmitted Data" for both ends. PURPOSE AND SCOPE OF COVERAGE - This standard is applicable to the interconnection of data terminal equipment (DTE) and data circuit-terminal equipment (DCE) employing serial binary data interchange. PURPOSE AND SCOPE OF COVERAGE - This standard is applicable to the interconnection of data terminal equipment (DTE) and data circuit-terminating equipment (DCE) employing serial binary data interchange. PURPOSE AND SCOPE OF COVERAGE - This standard is applicable to the interconnection of data terminal equipment (DTE) and data communication equipment (DCE) employing serial binary data interchange. If a star configuration is unavoidable, special RS-485 repeaters are available which bidirectionally listen for data on each span and then retransmit the data onto all other spans.

These other standards provide the protocol and other requirements that are needed for two devices to transfer information. All three standards have annexes. The RS-232 standard includes secondary serial data circuits (secondary TX data, and secondary RX data), three clocks (timing elements) for synchronous serial data transfer, Signal Quality Detector, and more. Slew rate limited drivers will improve signal quality significantly with an unterminated network. RS-232 is very clear that is intended for a maximum bit rate of 20kbit/s. The forward recommends EIA/TIA-530, EIA/TIA-561, and EIA/TIA-574 for operation at higher bit rates. It is not clear as to what the actual standard name is for each release. RS-232 only defines connecting DTE to DCE, so when two computers are connected together this is outside of the standard. Half of the conductors in a 50 way cable are ground return wires. RS-422 includes the voltage levels of the two wires when a binary 0 or 1 is on the RS-422 lines, but specifically excludes the logic function of the generator or receiver. RS-422 specifies the electrical levels of one transmitter to one of more receivers on a single pair of wires.

The new IBM PC/AT serial port no longer used the RS-232 25-pin connector or signal levels, but IBM took care to ensure that the new serial port’s electrical levels would still work with existing serial port peripherals, requiring only a 9-pin to 25-pin adapter. While this is incorrect, many to this day still believe that the RS-232 standard includes things such as baud rate and the bit stream protocol used in the IBM serial port. But, the RS-232 connection from the computer to the modem would still be full-duplex. RS-232 specifies two connectors, a 25-pin (DB-25) and an alternate 26-pin connector (pin 26 is "No Connection"). If only one circuit is implemented then the connection is simplex or one way. One circuit (Signal Common) is required for all interface types. That board is better supported by Laurel interface cables and is designed for easy interface to Laurels gateway boards, which are LUSB485, LNET485, LNET1485, LWIFI485, LWFIX485.

Two circuits are for transmitting and receiving the serial data, circuit "BA" (TX data on pin 2) and "BB" (RX data on pin 3). A number of circuits are for handshaking and other functions. It defines a means of exchanging control signals and binary serialized data signals between data processing terminal equipment and data communication equipment, and is of particular importance when each is furnished by a different company. In a RS-485 cable, data typically flows in both directions along any particular wire, sometimes from the "A" of the first device to the "A" of the second device, and at a later time from the "A" of the second device to the "A" of the first device. This stopped the data flow to the receiving end, allowing the receiver to process the data in its buffer. Within such a system, RS-485 serves a pivotal role as a bridge, establishing communication of flow information between the central control system and each valve box. The flow meters relay flow information in real-time to the central control system via RS-485, halting the supply once the specified amount of reagent is dispensed.

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