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  • Mel Bishop
    replied
    Originally posted by edward kaeufer:
    My RS485 device uses the RTS to control data flow...
    Then you need to NOT put the RS in the "open com:x" parameters.
    If you do specify the RS, CS, DS or CD in the "open" statement,
    these control signals will be ignored regardless of the com
    port pin state.

    Assuming your external device defaults to hardware flow control,
    just open the com port with the basic parameters:

    "Open "Com1:9600,n,8,1""

    should do the trick. Make sure your device is on before you
    bring up the program. Otherwise, you will probably get a device
    time-out error.


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    [This message has been edited by Mel Bishop (edited June 11, 2003).]

    Leave a comment:


  • Guest's Avatar
    Guest replied
    The RS option deals with "request to send", an outboard signal
    which is changing states apparently by the pb com driver.
    My RS485 device uses the RTS to control data flow...


    Originally posted by Mel Bishop:
    1. Yes. If you have RS specified, its state is immaterial. RS
    will always be ignored. Ditto with CS, DS and CD.

    2. Control will probably be returned after writing the info
    to the comm buffer. Not necessairly to the port itself.

    Word of note: The com port(s) on a computer are RS-232. I don't
    know if they are compatable with RS-485 devices. If you have
    this configuration, you may need a converter for successful
    communication.




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    Leave a comment:


  • Mel Bishop
    replied
    1. Yes. If you have RS specified, its state is immaterial. RS
    will always be ignored. Ditto with CS, DS and CD.

    2. Control will probably be returned after writing the info
    to the comm buffer. Not necessairly to the port itself.

    Word of note: The com port(s) on a computer are RS-232. I don't
    know if they are compatable with RS-485 devices. If you have
    this configuration, you may need a converter for successful
    communication.


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    Leave a comment:


  • Guest's Avatar
    Guest started a topic com (serial port) library behvior

    com (serial port) library behvior

    I am trying to use pb in a rs485 environment and have 2 questions.

    1. Opened com port with option "rs" specified.
    Does this disable the functionality?
    aka: rts does not change states (on, off) before,
    during and after transmission of data?

    2. Is "print #n" blocking?
    aka: program control returns after data completely sent?

    Thanks
    Ed



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