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[ts-7000] Re: Cron job corrupting serial data received

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Subject: [ts-7000] Re: Cron job corrupting serial data received
From: "jeffmigliore" <>
Date: Tue, 04 May 2010 21:51:54 -0000
I find it interesting that none of responses have been concerning the original 
post about the USB keyboard.

--- In  Steve Weigold <> wrote:
>
> 
> I find it interesting that neither my original message NOR Tom's 
> response was sent to me.  I'll respond to both.
> 
> On 5/3/2010 10:05 PM, Dan Weese wrote:
> >
> > I suspect this is simply a failure of flow control.  If both ends of 
> > the serial connection observed Xon/Xoff, the cron SQL job could 
> > "pause" the serial port for long enough to finish and get off the pot 
> > via a lockfile.
> >
> Dan, while I appreciate your response, there are a couple of issues 
> here.  First, the source of the data that my 7200 is listening to does 
> not respond at all to Xon/Xoff, and for that matter does not handle 
> hardware control well either.  The others probably aren't worth getting 
> into now, but suffice it to say that I'm stuck with the architecture as 
> it exists.
> 
> >
> > Or, the device could quit writing to its own local MySQL instance and 
> > park everything on the far end.  I wouldn't host a database on the 
> > same device as my serial port handler.
> >
> 
> Also, not an option.  The device needs to be able to record data even in 
> the absence of a data connection to the remote server.  The only other 
> option would be to store the data in a flat file of some description, 
> but I shudder at the potential pitfalls there.
> 
> In general though, I would not have expected unrelated system operations 
> to corrupt the serial port buffer, and that seems to be what is 
> happening here.
> 
> And then Tom said:
> >
> > On Mon, May 3, 2010 at 5:28 PM, tom campbell 
> > < <>> wrote:
> >
> >     Off the top of my head, is it an SQL locking issue?
> >     If the cron "reader" some how locked an SQL record, would the main app
> >     stall?
> >
> >     just a thought
> >     tc
> >
> 
> Maybe Tom, but again, I wouldn't expect that to actually corrupt the 
> serial port buffer, only to delay getting characters out of it, which 
> wouldn't cause my problem.
> 
> Thanks for both responses.  Any other ideas?
> 
> Steve
>




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