USB & RS232 is full or half duplex.

Discussion in 'General Electronics Chat' started by aamirali, Jul 17, 2012.

  1. aamirali

    Thread Starter Member

    Feb 2, 2012
    415
    1
    USB & RS232 are full or half duplex. Can I xmit & receive data simultaneously.
     
  2. tpny

    Member

    May 6, 2012
    216
    0
    I believe RS232 is. There's tx and rx buffer. The other serial RS485 is half duplex, although u can run longer wires with it.
     
  3. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    USB is most definitely NOT full duplex. There is one signal pair and one power pair in a USB cable. Read Axelson, J.,USB Complete for more info on USB.
     
  4. HDowns

    New Member

    Nov 24, 2010
    5
    0
    Virtually yes, the program will think that works with a full duplex connection, because each USB-to-RS232 converter has buffers. But if you'll send large data blocks fast you'll see difference.
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    That was not the original question. USB in and of itself is not inherently full duplex. The UART with an RS-232 physical layer is inherently full duplex. A UART with an RS-485 physical layer is inherently half-duplex.

    The typical USB to RS-232 converter actually bridges the two network topologies by means of buffers. There may be conditions under which those buffers can overflow.
     
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