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

[Steve Weigold <>]

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 <m("dinkumsoftware.com","content");">are.com> 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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