RS422 485 SERIAL
With SUNIX patented Auto-Switching RS-422/485 and RS-485 AHDC™ technology, user can easily manage different serial interfaces selection and RS-485 signal direction control. Each serial port achieves data rates up to 921.6 Kbps and utilizes 16C950 UART with an on-chip 128-bytes hardware FIFO buffer for reliable, high-speed serial I/O. To learn more about Stratus Engineering’s design services, please contact us via email or call us at (858) 663-1841.SUNIX IPC-E2202S, Industrial 2-port RS-422/485 with Surge PCI-Express Serial Card, allows users to expand two RS-422/485 ports on PC-based system. And with this design engineering services firm at your side, you can explore the benefits of a serial analyzer instantly. The required connections are the subject of one of our upcoming blog entries.įrom turnkey design and manufacturing to supplemental engineering support, Stratus Engineering is committed to delivering consistent, high-quality results day after day. The main drawback to these adapters that they require an external power supply, usually 5V a wall transformer, to provide power to the transceiver IC’s.įor many RS232 to RS22/485 applications, particularly those that operate with cable lengths and baud rates that are within the RS232 specifications, it is possible to make cable connections that provide the conversion without additional electronics. A functional block diagram for a typical RS232 to RS422/485 conversion adapter is shown below. RS232 to RS422/RS485 conversion is normally accomplished using commercially available adapters that use RS232 and RS485 transceiver IC’s to provide the required voltage signaling translations. For +5V or logic “1” TX+ is +5V and TX- is 0V or GND and for -5V or logic “0” TX+ is 0V or GND and TX- is +5V. In practice the differential voltages are almost always +/- 5V. The differential voltages can range between +/- 200mv and +/- 6V, with positive voltage for logic “1” and a negative voltage for logic “0”. The transmitter applies voltages to the TX+ and TX- signals which the receiver interprets by subtracting the RX- signal from the RX+ signal. RS422/RS485 differential signaling uses a pair of wires to transmit voltages that represent logic “0” and logic “1”. For RS232 to RS485 conversion purposes we will only consider “point to point” RS422/RS485 configurations with two devices in this case RS422 and RS485 can be considered electrically identical. RS485 also supports half duplex and multi-drop configurations for networking multiple devices, but these configurations are beyond the scope of this discussion. RS422/RS485 use differential signaling and cable termination to increase interface speed and noise immunity. In practice nearly all modern devices us +5V for logic “0” and -5V for logic “1”. Signaling voltage levels for RS232 are +3V to +15V for logic “0” or “space” and -3V to
RS422 485 FULL
RS232 supports full duplex communication between two devices over the TX (transmit) and RXD (receive) lines as shown in the figure below. For the purposes of this discussion we can ignore the optional handshaking signals they are rarely used and don’t apply to RS232 to RS422/RS485 conversion. RS232 is the simplest interface, which consists of 3 wires: TX, RX, and GND. In many cases the conversion is required to interface an RS422/RS485 device to the RS232 port on a PC. Since both protocols are commonly used for the same or similar applications, it is often desirable or necessary to provide signal conversion between them. All three use the same basic logical protocol, but vary in their physical implementation, i.e., voltage levels and signaling. RS232, RS422 and RS485 are simple asynchronous serial protocols used in a wide range of commercial, industrial, and military applications.