It is possible that your cable connections are wrong.
Your 485 -> 232 converter should actually be set up as a 422 -> 232 converter.
RS422 is full duplex, RS485 is half duplex. Then TX+ is pin 1, TX- is pin 6,
RX+ is pin 4, RX- is pin 9. Also note that the COM2 header uses non-standard
pin numbering.
On the RS232 side, you should probably use a straight cable, not a null modem.
Since RS485 is half duplex, there is no such thing as a RS485 null modem cable.
To do a loopback test, connect COM2 header pins 1 to 4, 6 to 9. Again, be sure
to use the correct non-standard pin numbering.
--- In "khouryelie" wrote:
>
>
> thanks everyone but i am starting to think its not my code that's wrong it's
> just the cable connections
>
> i am configuring with my code port COM2 to 485 FULL DUPLEX
> but i am using a null modem cable THE SAME I USED TO TEST ports 232 and
> connecting that modem cable to a converter cable from 485 -> 232 then reading
> with minicom Through a 232 TO USB
>
> I think that sending from 485 port to a null modem( that was used with
> success with 232 ) is the mistake
>
> ANYONE KNOW IF I should get A 485 null modem cable ?
> IS THERE ANY DIFFRENCE between NULL MODEM CABLES ? SOME FOR 232 QND OTHES FOR
> 485 FULL DUPLEX ?
>
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