Multiple RS232 to onr USB

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Smartell

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May 12, 2020, 6:30:50 AM5/12/20
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Hi,

Don't know if it is ok to ask this question here but ...i have a dual RS232 to USB...that is an adapter cable with one USB and two RS232 connectors works fine...How do they do that?

The reason i ask, curiosity aside, is that i "happen to have" a board with four RS232 to serial adapters ...nice connectors and all that i would like to re-use if possible They are based on the MAX232E chips so i have four pairs of TTL  TC/RX ... how do i cram that into one USB ?

/M

Keith Young

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May 15, 2020, 6:23:50 AM5/15/20
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The reason i ask, curiosity aside, is that i "happen to have" a board with four RS232 to serial adapters ...nice connectors and all that i would like to re-use if possible They are based on the MAX232E chips so i have four pairs of TTL  TC/RX ... how do i cram that into one USB ?

To clarify this: you have a board with some good connectors.  If they're MAX232's rather than MAX3232s it'll be 5v on the other end rather than the pi's 3.3v logic level.  We'd like to have those feed into a single usb connection which presents as multiple devices (e.g. /dev/ttyUSB0, /dev/ttyUSB1 etc.) on the connected system in the same way that a dual-serial to usb adaptor does.

I don't know how this works (hopefully someone else will).  I do have one of those two-way adapters on my boat which I currently can't get to because of lockdown restrictions.  I'm interested in the answer too so will investigate this myself out of curiosity but electronics is not my strong point....

Keith Young

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May 15, 2020, 5:55:07 PM5/15/20
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With the previous "Electronics is not my speciality" comment and thus take this with no more authority than something said by some random guy in a bar after a few Dark 'n' Stormies....might something like this be of interest?
?  Logic level is 3.3v but it says "5v tolerant".  But really almost anyone else who actually knows something about electronics would be better placed to advise...

he...@seacoastmarine.ca

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May 15, 2020, 6:11:57 PM5/15/20
to Keith Young, kplex

Using the chip a lot and working very well.

 

Recommend the development tool:

https://www.mouser.ca/Embedded-Solutions/Engineering-Tools/Analog-Digital-IC-Development-Tools/Interface-Development-Tools/Images/_/N-cxbit?keyword=FT423

 

Still you require a RS422 to UART converter

 

Henk

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