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+--- Thread: Export Block Descriptor + exp-File circularized = IOError (/thread-783.html)



Export Block Descriptor + exp-File circularized = IOError - dominik.windhab - 28-11-2018

Hi!

I am reading the historical table in my basic script with a block descriptor. Works fine, except that opening the block may take up to 7 or 8 seconds if the block contains a lot of data. However, there is the problem that when I am reading the historical table in my script and at the same time the following events occur in the Event Logs:

 Event 23607, exp-File circularized, Originator scp
  Event 934, pcmflash-File was circularized, Originator scp

I will receive an IOError during the read process:

  $nextLine$ = GET 1

I tried to use some error catching mechanism (https://techforum.ewon.biz/thread-387-post-2616.html) but this is not working since I am using it in a function.

Any hints what the Events are actually telling me? And of course, any suggestions how to solve that?

Best regards,
Dominik


RE: Export Block Descriptor + exp-File circularized = IOError - simon - 28-11-2018

Dominik,

This error is "normal" and occurs because you are reading the Historical Data files while the FIFO process is executed.
Indeed, to act as a FIFO buffer for Histo logging, the eWON works with several small files of Histo Data that are deleted (oldest one) and recreated. So, when the Histo Logging memory is full and the newly created small data file is full, the eWON deletes the oldest small data file and recreate a new one.
If you read the data of any manners (EBD, script, Datamailbox,..) while the eWON is doing the above process, you get this error. Normally, it does not cause a critical problem as the data export will work fine at the next try.
As you can imagine, the probability you can get the error increases with the amount of data you record (number of tags) and the frequency you use.

In conclusion,
You can do nothing to avoid the problem, except recording less data and/or decrease the frequency...
If you want to catch the error, you should do this process outside the function unfortunately --> See https://techforum.ewon.biz/thread-387.html

Simon


RE: Export Block Descriptor + exp-File circularized = IOError - rahul - 14-02-2022

(28-11-2018, 01:44 PM)simon Wrote: Dominik,

This error is "normal" and occurs because you are reading the Historical Data files while the FIFO process is executed.
Indeed, to act as a FIFO buffer for Histo logging, the eWON works with several small files of Histo Data that are deleted (oldest one) and recreated.  So, when the Histo Logging memory is full and the newly created small data file is full, the eWON deletes the oldest small data file and recreate a new one.
If you read the data of any manners (EBD, script, Datamailbox,..) while the eWON is doing the above process, you get this error.  Normally, it does not cause a critical problem as the data export will work fine at the next try.
As you can imagine, the probability you can get the error increases with the amount of  data you record (number of tags) and the frequency you use.

In conclusion,
You can do nothing to avoid the problem, except recording less data and/or decrease the frequency...
If you want to catch the error, you should do this process outside the function unfortunately --> See https://techforum.ewon.biz/thread-387.html

Simon

Hi Simon, 


Can ewon goes unreachable due to the above error which is mentioned by Dominik ?


Thanks,
Rahul


RE: Export Block Descriptor + exp-File circularized = IOError - simon - 16-02-2022

Rahul,

The Web interface also uses Export Block Descriptor so yes, it can be unreachable during this time.