AFAIK, RS232 may have signals as high as 12 V positive *AND* negative,
so the 4066 should have its power supply of at least 24 V and its Vss
pin at -12V refered to the system ground.

I thing that maybe you can add some AD232 or similar for RS232 lines and
use any mux you like. This should increase your budget, but I think it
would be much more eficient.

Hope this helps
Francisco

Augusto Yipmantin - OA4CVT wrote:

>Hi all,
>
>Here again with aquestion about how to read 2 devices with a single RS232
>Port on my laptop.
>The idea is to read data from a GPS unit (DB-9 "A" connector) and keep
>conected a TNC unit (DB-9 "B" connector) via the RS232 COM port of my laptop
>(DB-9 "C" connector).
>I4m not sure if a couple of CD4066 Quad bilateral switch ( one for the "A"
>and one for the "B" connectors ) will be enough in speed to switch the
>incoming and outgoing data across the COM port.
>Using a PIC16F84A-20 I can sense the DCD from the GPS "A" connector and
>enable the the CD4066 to switch on the communication between the PC and the
>GPS, then keep off both CD4066 when no DCD is detected, same procedure with
>the DCD from the COM port when the outgoing signals must flow to the TNC and
>no to the GPS.
>
>Any idea or suggestions are wellcome.
>
>Regards,
>
>Augusto, OA4CVT
>
>
>******                                       ******
>* GPS*                                       *TNC*
>******                                       ******
>      *                                                *
>      *                                                *
>      *         **********                   *
>      ****** SWITCH ************
>                 *    BOX    *
>                 **********
>                          *
>                          *
>                          *
>                   *********
>                   * COM    *
>                   * PORT   *
>                   *********
>
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>
>

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