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

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Subject: Re: [ts-7000] Cron job corrupting serial data received
From: Jim Jackson <>
Date: Wed, 5 May 2010 09:38:49 +0100 (BST)


On Tue, 4 May 2010, Steve Weigold wrote:

>> 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.

You know, I'd shudder less. We must have different backgrounds.
At least you'd be in control - sql databases tend to have a mind of their 
own.

> 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.

If the kernel disables interrupts for a period, then the serial interrupts 
will not be serviced and you will lose data. Have you tried hosting the sql 
database on SDcard or CFdisk (I forget which platform you are using)?
Or, purely for diagnostic purposes, have you tried it on an NFS mounted
paritition?

>
> 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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