Serial port operation -

Bob Goodwin bobgoodwin at
Tue Nov 29 23:18:28 UTC 2011

On 29/11/11 17:58, Maciek Borzecki wrote:
> At Tue, 29 Nov 2011 17:48:45 -0500,
> Bob Goodwin wrote:
>> On 29/11/11 16:14, Tim wrote:
>>> On Tue, 2011-11-29 at 14:14 -0500, Bob Goodwin wrote:
>>>> I have two F-15 computers with a program that should be toggling
>>>>           RTS and DTR on the serial port. One works as expected this one I
>>>>           am on now does not.
>>>>           I haven't had much to do with the serial port and don't know how
>>>>           to troubleshoot it.
>>>>           Can someone offer a suggestion where to begin?
>>> Obvious first line of thought:  Are you using two different serial
>>> cables?  And, if so, is the non-working one fully wired?
>>          I eliminated that possibility and swapped the cables, one worked
>>          "out of the box" this one doesn't. I was hoping it would be some
>>          configuration problem but don't know where to look. One is
>>          F16-32bit, this one 64 bit, however they are different
>>          computers, this one an HP, the other Dell, both of roughly the
>>          same vintage.
> Disable flow control and connect through a null modem cable to another
> PC. Fire up minicom, set both to 8N1, same speed for both and you
> should be able to see characters pop up on the other end while typing.

        I would have to make a null modem cable, probably have parts for
        that but it seems improbable that that will work if I am not
        seeing the voltage switch at RTS and DTS. I hate to make a
        bigger project out of it than necessary. I see that minicom is
        apparently installed by default so if need be it is there but
        it's been years since I messed with that ...

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