[time-nuts] FE-5680A OSMT connector / RS232

James Peroulas james at peroulas.com
Tue Dec 11 15:30:25 UTC 2012

Thanks for all your suggestions!

Ends up that I seem to have found yet a different version of the 5680a :)
My DDS board did have an RS232 level shifter but for some reason, the RS232
TX signal was not being brought out to the 5 pin connector. Once I soldered
the TX wire directly to the SP233ACT level shifter (pin 5), I was able to
communicate with the device.


Date: Sun, 09 Dec 2012 23:25:25 -0800
> From: Hal Murray <hmurray at megapathdsl.net>
> To: Discussion of precise time and frequency measurement
>         <time-nuts at febo.com>
> Subject: Re: [time-nuts] FE-5680A OSMT connector / RS232
> Message-ID:
>         <20121210072525.7B0EF80003B at ip-64-139-1-69.sjc.megapath.net>
> Content-Type: text/plain; charset=us-ascii
> james at peroulas.com said:
> > I'm not able to get it to respond to the 'S' command and when I measure
> the
> > voltage on the RS232 TX pin (#2 from the left) it's always 0v. Shouldn't
> it
> > be -12v when idle?
> Newer RS-232 allows 6V rather than 12.
> In practice, it's not all that uncommon for designers to save a chip and
> just
> send 5V CMOS signals.  That works fine for short distances.
> If you can get a scope on it, sometimes embedded boxes send out a hello
> message at power up.
> I'd also check pin 3 in case you or they got things swapped.
> --
> These are my opinions.  I hate spam.

*Integrity is a binary state - either you have it or you don’t.* - John

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