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Need high speed RS232 interconnect

Discussion in 'Electronic Design' started by Boki, May 29, 2006.

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  1. Boki

    Boki Guest

    Hi All,

    I need a RS232 (PC to embedded device) interconnect/interface that
    support 460.8Kbps/921.6Kbps ( higher is better )

    Thank you very much!

    Best regards,
  2. Pooh Bear

    Pooh Bear Guest

  3. Boki

    Boki Guest

    Pooh Bear 寫�:
    In fact, I buy a USB to UART converter yesterday, the title said it
    support 1Mbps.. when I installed to PC... it only support 12800Kbps for

    so, I give up USB.. I try to find PCI. And then I found SUNIX's PCI
    RS232 card.

    Best regards,
  4. Boki

    Boki Guest

    Boki 寫�:
  5. Pooh Bear

    Pooh Bear Guest

  6. Boki

    Boki Guest

    Pooh Bear 寫�:
    Thank you very much to consider the cost, but right now, this is for my
    development tool only.

    and my app needs two way communication....

    Best regards,
  7. Jim

    Jim Guest

    The FDTI integrated circuits would work for your requirement, although as
    I recall, you probably need USB2 on your computer to support the higher
    speeds. If you use RS485, this website claims up to 3 MB data rate.
    960 KB for RS232 if you want RS232.



    11:11 Pacific Time Zone
    May 29 2006

    International Time
    18:11 UTC
  8. David

    David Guest

    FTDI devices are USB 1.1 (you can connect them to a USB2 port, but they
    still only run at 12 MBit). They'll do 1 MB RS-232, or 3 MB RS-485 or
    TTL level (i.e., they can do signalling at 3 MB, but RS-232 drivers are
    limited to 1 MB).
  9. Guest

    Jim skrev:
    you don't need usb high speed to do 1Mbps.
    The FTDI FT232 will do 921.6Kbps but windows won't always let you
    a serial port to anything but the <= 115.2kbps standard speeds, so you
    have to
    go into the driver setup and tell the device to alias one of the
    standard speeds to 921.6kbps. That way the device driver will know that
    when it is told run at e.g.
    300baud it should program the baudrate to 921.6kbps

  10. Guest

    Is your target device doing +12/-12V device operation .. ? or TTL?
  11. Key thing, is that it is unlikely that the embedded device is 'RS232', if
    it supports this high a data rate. RS232, is an electrical signalling
    spec, _not_ the specification for asynchronous serial data, which the term
    is often used (incorrectly) for. I'd strongly suspect that the embedded
    device is 'TTL serial', _not_ 'RS232', since this is beyond the specified
    rates supported by RS232, and even using extrapolation from the RS232
    figures, the cable lengths that would be supported at this rate, would be
    Hence, making the assumption, that what is needed is actually TTL
    asynchronous serial, _not_ 'RS232', then the second question is whether
    the device actually supports this rate without handshaking. Few devices an
    handle this sort of rate continuously. Now looking at the USB interfaces
    that mny posters have mentioned. A lot of such devices support high
    interface rates like this, but only on the local interconnection. Most
    USB-RS232 adapters, are at heart USB HID devices, and even those
    supporting 'high speed' operation, will only achieve 64,000Bps max, and
    therefore will have trouble handling a serial bus over 640,000bps. Above
    this, they only transfer at these rates for a short moment, till the
    buffer is full, and if 'RS232' signalling is used, the maximum cable
    lengths are then only a few inches to the device.
    Start by saving a lot of effort, and get the data sheet for the 'embedded'
    device. If it is yet to be designed, look at a standard like RS422, rather
    than RS232. Once you actually have the signalling standard involved, then
    there are PCI cards, or block mode USB devices, that can comfortably
    handle signalling at these rates. At present, your question is a bit too
    'open'. There are hundreds of devices that can operate a serial bus at
    these higher rates, but few that can do it for any length of time, and if
    the cabling needs to be more than a very few inches long, it is unlikely
    that the connection is 'RS232'.

    Best Wishes
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