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

[Dan Weese <>]

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.  

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.

Again, just a thought.

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

On Mon, 2010-05-03 at 18:18 -0400, Steve Weigold wrote:
>
>
>
> >
> >
>
> Good Evening Everyone,
>
> I have an application running continuously on a TS-7200 which collects
> data received on /dev/ttyAM1, parses it to a small degree and stores
> it to a MySQL database on the device. I have the communications port
> set up as non-blocking, and just poll the port with "read" to retrieve
> data. Under normal circumstances, everything works fine.
>
> I have another application which is called as a cron job every five
> minutes. That application queries the data from the local database
> and synchronizes it with a database on a remote MySQL server. The
> sync application outputs only to a file and to the remote database.
> It currently has no interaction between the first app, or any of the
> comm ports.
>
> The problem I'm finding is that every five minutes when the cron job
> runs, something is causing the incoming data to essentially stop.
> Nothing appears to recorded by the first application during the time
> that the sync application is busy.
>
> To the best of my ability to search, the comm ports are set correctly,
> and as I said, the data collection application runs fine by itself.
>
> Can anyone make some suggestions on where to go from here? Even if
> the sync application caused the collection app to pause, I would have
> expected the data to accumulate in the serial port buffer and be
> available when the collection app resumed, but it does not. It just
> seems to vanish.
>
> I'd appreciate any suggestions.
>
> Steve
>
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>

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