[PARPORT] Port Multiplexor Problem

From: Mike Murphy (mike@flipper.eskimo.net)
Date: Fri Feb 02 2001 - 11:21:04 EST

  • Next message: Tim Waugh: "Re: [PARPORT] Port Multiplexor Problem"

    This should be an easy question for the readers of this list.

    I recently purchased what I believed to be a port multiplexor (4 way), but
    the parport driver doesn't seem to recognize it and only recognizes
    whichever printer is currently selected on the device. I suspect the
    multiplexor doesn't speak the 1284.3 protocol, if this is even a possibility
    (haven't read the spec or have much experience with these devices). It
    comes with some windows software which will (allegedly) operate the

    So I suspect the device is capable, but operates in an unexpected way with
    respect to the driver. The multiplexor is a Keyshare Bi-Tronics Plus
    IEEE-1284 Auto Switch http://www.cwol.com/ieee4way.htm

    In case this helps... I added a printk() in the mux_present() function in
    drivers/parport/daisy.c, and cpp_mux(port, 0x51) needs to return a value of
    3 in order for a multiplexor to be detected. In my case, it returns a value
    of 1. Does this basically mean that my mulitplexor is "not the right kind"?
    Any suggestion on "what the right kind" would be? This product throws
    around the term "IEEE 1284", so I thought I would be in the clear... but I
    am suspecting they were actually refering to the connecting cables.

    Any insight would be appreciated. I am willing and able to experiment with
    any experimental patching if necessary.


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