Hi Listers,

I am looking for a method of sharing a 9-pin serial port between RS232 &
RS422/485 drivers.

The pin-out would thus be :

Pin        RS232        RS422/485
        Sig     Dir     Signal  Dir

 1      N/C             N/C
 2      Rx      In      Rx-     In
 3      Tx      Out     Tx+     Out
 4      0V              0V
 5      0V              0V
 6      0V              0V
 7      RTS     Out     Rx+     In
 8      CTS     In      Tx-     Out
 9      N/C             N/C

As can be seen there are clashes between outputs and inputs.

I need advice an possible ways to acheive this :        tri-stables drivers
perhaps (can the 422 ones take 232 oltages when tri-stated??)
                                                FET switches to route the
signals (Signetics ??)
                                                Relays (expensive ?)
                                                Muti Mode chips (SIPEX -
heard bad things about them)

Help....




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| Mark Birks                       |
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