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Owin,owout — Parallax Forums

Owin,owout

ArchiverArchiver Posts: 46,084
edited 2003-02-13 17:21 in General Discussion
One way Communiation (example) Commands sent from BS2P to 30 other BS2p'S
all at on time

Dose anyone have experience doing this?

Regards, Folks

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 02:56
    OWIN and OWOUT are for Dallas/Maxim 1-Wire communications. The BS2p and pe
    can use these commands to connect with 1-Wire devices, but not with each
    other.

    You can use open-mode serial communications to connect several Stamps on one
    line [noparse][[/noparse]though you may have some loading issues with 30]. Consult the SERIN
    and SEROUT section of the manual -- it shows how to connect multiple slaves
    to a single master.

    -- Jon Williams
    -- Parallax

    In a message dated 2/12/2003 7:42:01 PM Central Standard Time,
    lwindrem@p... writes:

    > One way Communiation (example) Commands sent from BS2P to 30 other BS2p'S
    > all at on time
    >
    > Dose anyone have experience doing this?
    >
    > Regards, Folks
    >



    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 03:23
    I would look into RS485. Dallas / Maxim makes some driver chips similar to
    the MAX232 that will allow multiple devices to share communication lines.

    Original Message

    > OWIN and OWOUT are for Dallas/Maxim 1-Wire communications. The BS2p and pe
    > can use these commands to connect with 1-Wire devices, but not with each
    > other.
    >
    > You can use open-mode serial communications to connect several Stamps on
    one
    > line [noparse][[/noparse]though you may have some loading issues with 30]. Consult the SERIN
    > and SEROUT section of the manual -- it shows how to connect multiple
    slaves
    > to a single master.

    > > One way Communiation (example) Commands sent from BS2P to 30 other
    BS2p'S
    > > all at on time
    > >
    > > Dose anyone have experience doing this?
  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 04:39
    HI Jon
    Is it possible to use a transitor connected to a I/O pin to send
    the serout signal in this project
    I don,t need an answere back from the slave stamp. I have a good
    Gnd.(VSS) but only one spare signal
    Wire.The reason for the extra drive power is so that I can Keep the
    impedence low.

    Regards Larry
  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 05:14
    Here is the data sheet for the 485 driver IC from Maxim:

    http://pdfserv.maxim-ic.com/arpdf/MAX1487-MAX491.pdf


    Original Message

    > I'd be inclined to go with Bill's idea and use an RS485 driver.

    > > Is it possible to use a transitor connected to a I/O pin to send
    > > the serout signal in this project
    > > I don,t need an answere back from the slave stamp. I have a good
    > > Gnd.(VSS) but only one spare signal
    > > Wire.The reason for the extra drive power is so that I can Keep the
    > > impedence low.
  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 05:14
    I'd be inclined to go with Bill's idea and use an RS485 driver.

    -- Jon Williams
    -- Parallax

    In a message dated 2/12/2003 10:47:18 PM Central Standard Time,
    lwindrem@p... writes:

    > HI Jon
    > Is it possible to use a transitor connected to a I/O pin to send
    > the serout signal in this project
    > I don,t need an answere back from the slave stamp. I have a good
    > Gnd.(VSS) but only one spare signal
    > Wire.The reason for the extra drive power is so that I can Keep the
    > impedence low.
    >
    > Regards Larry



    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 05:36
    Hi

    I do use the Max491 & the LTC491 in my systems, this is a unique
    situation,
    I already have the system in place boards manufactured wiring in place
    and I do
    Not have two wires in the system to accommodate RS422 or RS485 . I
    only have
    A Single wire. See Page 305 in Parallax Manual 2.0 . I Just want to
    increase the
    Drive power (Figure5.36:

    Regards Larry
  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 09:11
    >One way Communiation (example) Commands sent from BS2P to 30 other BS2p'S
    >all at on time

    >I already have the system in place boards manufactured wiring in place
    >and I do Not have two wires in the system to accommodate RS422 or RS485 . I
    >only have A Single wire. See Page 305 in Parallax Manual 2.0 . I Just want to
    >increase the Drive power (Figure5.36:
    >Regards Larry

    >Is it possible to use a transitor connected to a I/O pin to send
    >the serout signal in this project I don,t need an answere back from
    >the slave stamp. I have a good
    >Gnd.(VSS) but only one spare signal Wire.The reason for the extra
    >drive power is so that I can Keep the
    >impedence low.

    Is one particular Stamp always the SEROUT master, and the other 30
    will always be listening with a SERIN?

    In that case there is no need for the open baud mode depicted in
    figure 5.36. The master stamp can drive the line both high and low
    in the driven baud mode. If you need more drive current, then use a
    CMOS chip like the CD4050, which has 6 big CMOS inverters in one
    package. Put all 6 in parallel to drive a low impedence like a 75
    ohms termination.

    How far a distance are the Stamps apart and is there danger of noise
    pickup on the wire?

    -- Tracy
  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 13:31
    Hi Tracey

    1. The BS2 40P is the master always.
    2. The 30 Stamps (Pic12F629) all slaves.
    3. I have the BS2 40P 1 (PIC12F629) on a 65' cable 8 con. With RJ45 plugs &
    Modular jacks.
    4. Yes there is chance of electrical noise
    5. The info I send is four single Byte commands. Ect. Dec 0,1,2,3,4


    The test setup I have at the present appears to be "BOILER PLATE"
    The CMOS Chip sounds like a plan.
    I have talked to Chuck he told me you would be the person to talk to.

    Thank you for the response

    Regards Larry
  • ArchiverArchiver Posts: 46,084
    edited 2003-02-13 17:21
    Hi Larry,

    Is this a "star" arrangement, with each slave off in a different
    direction on 65 foot cables, all attached to the central BS2p? Just
    for safety, I'd put a resistor of 200 to 1000 ohms in series with the
    inputs to each slave PIC.

    A CMOS CD4050 buffer or one of the 8-pin RS485 chips that people
    suggested would isolate the Stamp from the line and also provide more
    drive current. For one wire, you would just use one side the the
    '485 driver. Better to use the full differential, but KISS works too
    with that one wire. You could use multiple drivers in one package to
    divide the 30 slaves into several groups, driven by one Stamp pin.

    Put in a checksum or redundancy to allow for noise.

    -- Tracy


    >Hi Tracey
    >
    >1. The BS2 40P is the master always.
    >2. The 30 Stamps (Pic12F629) all slaves.
    >3. I have the BS2 40P 1 (PIC12F629) on a 65' cable 8 con. With RJ45 plugs &
    >Modular jacks.
    >4. Yes there is chance of electrical noise
    >5. The info I send is four single Byte commands. Ect. Dec 0,1,2,3,4
    >
    >
    > The test setup I have at the present appears to be "BOILER PLATE"
    >The CMOS Chip sounds like a plan.
    >I have talked to Chuck he told me you would be the person to talk to.
    >
    >Thank you for the response
    >
    >Regards Larry
    >
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