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CR3000 / LoggerNet Table Definition Error

dberdes Oct 8, 2020 12:04 PM

I have a CR3000 (OS 32.05) connected to LoggerNet 4.6.2 via FreeWave wireless transceivers.  The scheduled download is every five minutes for new data.

Concurrently I am using an NL116 with a 1 GB industrial strength CF card.  Periodically the CF card is removed from the system to download data.  Whenever I remove or insert the card, I get an "Invald Table Definitions" error on LoggerNet and the scheduled download is halted.  It is easily fixed via "Update Table Definitions - Merge" on LoggerNet but I never had this problem before.  I have other systems running this same configuration with no issues.

Any suggestions?

jtrauntvein Oct 8, 2020 02:04 PM

One of the things that the datalogger reports with its table definitions is the number of records stored in the table.  When a CardOut() instruction is used, the datalogger table extends its storage into the storage device.  When the storage device is removed, that will cause a change in the table size (again in terms of number of records) and, if a new card is added, storage space will again be reallocated.  If the replacement is relatively quick and the cards are similar in layout and content, LoggerNet may not notice the change.  If, however, the new card has different size or is filled with other things, the number of records that are allocated for an auto-allocated table will change and this will, in turn, change the table definition signature.  

Fortunately, the result is not as drastic as it sounds.  If LoggerNet already has the table definitions for the datalogger and detects that its table definitions are invalid (this generally happens when LoggerNet attempts data collection and the response code indicates an invalid signature), LoggerNet will refresh its table definitions by first asking for a .TDFS (or table definitions summary) file.  This file will report the set of tables, their definitions signatures, and the number of records allocated.  If LoggerNet can reconcile its own table definitions by updating the number of records, it does not need to do anything more for that particular table.  This reduces the cost of refreshing table definitions considerably although it will still have the effect of temporarily interrupting scheduled collection.

If the problem is significant, you could consider using the TableFile() instruction to write data files to the card.  This will not necessarily "extend" table storage (although it can with some options) but it will write the data files to the card in baled segments.

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