On a sunny day (Sun, 3 Jun 2018 23:13:42 +0000 (UTC)) it happened Martin
Gregorie  wrote in :

>On Sun, 03 Jun 2018 07:44:20 +0000, Jan Panteltje wrote:
>
>> On a sunny day (Sun, 03 Jun 2018 07:07:24 GMT) it happened Jan Panteltje
>>  wrote in
>> :
>>
>>>The real RS232 RXD from the D connector comes in on pin 13,
>>>and goes to your 3.5mm connector's rx.
>>
>> Should read:
>> and goes from pin 12 to your 3.5mm connector's rx.
>
>I don't have that many pins :-)

No problem, pins are cheap :-).
Sorry for unclear drawing.
But for the record:
  http://panteltje.com/pub/MAX232_wiring_IMG_6422.JPG
a simple example of interfacing logic level to RS232 level with a MAX232.



>Made up a cable: D9-> 3.5 stereo jack cable with handshake jumpers (7-8,
>1-4-6) today and tested it on my old pFranc USB->RS232 adapter using my
>termination/test box to monitor signal levels. It worked as expected when
>driven by ptlrc on both RPi and Lenovo T440 (Fedora 27) hosts. My 'scope
>showed a good solid 12v signal when it was on the RPi. Ran out of time
>then (other engagements), so will try it on the KRT2 radio tomorrow.


Sounds OK.
Having a scope is a big plus with all that tronix,
still have a 10 MHz analog myself.
designed a small digital one too:
 http://panteltje.com/panteltje/pic/scope_pic/

hey an other MAX232...

:-)

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