[ct-user] Serial interface & keying

Ron Stordahl Ron Stordahl" <ron.stordahl@DIGIKEY.COM
Mon, 10 Jan 2000 16:37:01 -0600

Steve said:
> Hi Ron,
> Sorry.  I was a little too narrow;  the pins 4 and 7 previously mentioned
> to the RTS and DTR pins on a 9-pin RS-232, as opposed to their
counterparts on
> a 25-pin.
> It's actually quite common for the RS-232 / TTL level-shifting and
inversion to
> be done by logic inside the connector shell hanging off those two lines
> power;  it's truly 'orrible, but it works and beats having to
> power another funny little box somewhere.  Whether such an arrangement
> have enough 'oomph' off just the RTS line, so freeing up the DTR line for
> keying, will remain to be seen.
> Certainly it seems as though Waldek has an 'all-singing, all-dancing'
> combination along these lines happening already.
> 73,        Steve

OH!  I was only thinking of the 25 pin assignments.  I was not aware that
anyone would try to get their power from RTS and DTR, but some
people........Now I realize that it is done, there is an entire TNC built
into a 25 pin RS232 hood and it gets it power from the interface, I thought
that maybe the +12 and -12 might be provided on a pair of pins.  Guess not!

But back to CW keying using DTR..what needs to be done is Ken should make
the changes to COMTSR so that it does not immediately assert DTR when it
starts, making for a very unpleasant experience.

Probably just to assure compatibility COMTSR should have a start option
where you can pass to it if you want it work as it does now or if you want
it to start with DTR low (as any users doing DTR keying would like).

So again I hope you are reading the mail on us Ken.

Ron N5IN

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