On 29/11/11 18:46, Maciek Borzecki wrote:
> At Tue, 29 Nov 2011 18:18:28 -0500,
> Bob Goodwin wrote:
>> 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 ...
> If you've never seen it work with those PCs,
It works perfectly with one computer.
> then disable hardware
> flow control if possible. I've seen it to fail occasionally with some
> newer hardware (as if anything aside from data and ground would not be
> wired). By disabling hardware flow control RTS/CTS signalling is not
> used at all.
All I need is for RTS to toggle, no data is being transfered.
> If it's not possible to disable hardware flow control for that
> particular application, then start with the lowest layer in the stack
> - check the cabling. After that you may try to see see if the port is
> getting configured correctly (run it under strac and look for ioctls -
> verify with manpages tty_ioctl(4) and termios(3)).
I don't know how to deal with these commands, will have to read
further.
Thanks,
Bob
.
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