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RS-232 & RS-485 circuit

Other Parts Discussed in Thread: TRSF3238E, TRS3238E

Hello,

Customer wants to make RS-232 & RS-485 circuit like as attached block diagram.

Can this block work well?

Could you recommend RS-232 & RS-485 product for this block diagram?

Regards,

Nicky

RS232_485.pdf

 

  • Nicky,

    How many data lines in each blue line?
    Is it...
    2 = RS232: RX, TX
    2 = RS485: (A/B)
    2 = UART: RX,TX
    1 = GND

    2 pins left, could be used for RS-232 flow control RTS,CTS
  • Hi Ronald,

    Customer wants to use RS232 / RS485 & RS422 / 1.8V Normal UART  interface but will use 1 interface at a time by choosing with Analog Switch.

    If she wants to make this function like as attached block diagram(RS232_485_Rev.2.pdf), she can use only PHY devices(RS232 / RS485 & RS422 / 1.8V Normal UART)?

    And can she use any analog switch for this block?

    Please see attached block diagram and let me get your reply.

    Regards,

    Nicky

    RS232_485_Rev.2.pdf

  • Nicky,

    I don't recommend signal switching on the DB9 connect. Use a RS-232 device and RS-485 device with disables.

    For RS-232 device try TRS3238E or faster TRSF3238E. I assume that this connect to a computer (DTE) so I made the RS-232 side DCU. I also do not recommend sending an un-buffered UART data. The RS-485 device should be full duplex to support RS-422 and RS-485.

    I do not know a standard for RS-232 and RS-485 on same port, so I made this pin map.

    Direction PIN RS-232 RS-485
    Out 1 DCD A
    Out 2 RX B
    In 3 TX  
    In 4 DTR  
    GND 5 GND GND
    Out 6 DSR Y
    In 7 RTS  
    Out 8 CTS Z
    Out 9 RI