Now more commonly used RS232 serial 9–pin d-shaped serial [DB9] and 25–pin d-shaped serial [DB25], the maximum communication distance of up to [15m]. The short distance between two devices close, 232 of them with 232 cable directly connected to the serial port if distant, via modem (MODEM) connected.
“Negative logic“—the output is represented by +5V~+15V ,-5V~-15V said the logic [logic 1].
“Single drive“—through the data sender [TD] output driver circuit, and signal GND as reference points.
“Receiving“—by the data receiver [RD] enter the receiving level and to signal GND as the reference point.
RS232 wire –
To achieve [point-to-point bi-directional communication] requires 3 communication cable, host the data sender [TD] with data from the receiver [RD] connected to host the data receiver [RD] with data from the transmitter [TD] connect two signal ground [GND] is directly connected to.
RS232 serial ports cannot be directly connected to the RS485 serial port—because they have the same electrical standards; serial converters available on the market, must pass through the converter to connect. Also, do not plug, and plug when there is at least one end is powered down, or easily damaged serial port.