This topic describes detailed causes and troubleshooting for issues and errors associated with the Weatherlink logger archive data and that have not been fixed by the Simple remedies.

The root cause of archive download issues that have not responded to simple fixes is usually data corruption either in the logger itself or on the computer hard drive. To troubleshoot such problems involves trying to narrow down exactly where the corrupt data is being stored and clearing, deleting or writing over that data.

A few important initial points: First (and assuming that this is an installation that was previously working successfully, ie that it’s not a new installation, an attempted upgrade etc), reinstalling the Weatherlink software is rarely the answer to problems that relate only to archive downloads. If all the other possible investigations and fixes have been tried but failed then reinstallation can also be tried of course, but it should be more of a last resort – work first through the other suggestions below and don’t waste time trying reinstallation early on.

Second, deleting (‘clearing’) the logger of all its data is occasionally the only way of fixing archive download issues, but no-one wants to lose data and there are often other solutions that will fix the problem, so once again clearing the logger should be left as a last resort.

Third, there’s a distinction between download issues that happen just once in a while and those that start to occur more often. For very occasional problems it’s usually not worth the time and effort to go further than correcting the immediate error. Very occasional data corruption can occur with any computer-linked system and due to causes as unlikely as cosmic rays – it’s entirely possible that a one-off issue might never recur and that the original cause could never be known for sure. But if the problem does start to happen repeatedly then clearly further investigation is merited. See the final section below on ‘Recurrent archive download problems’.

Troubleshooting steps

Once again, be sure to try the Simple remedies first. But if the archive downloads continue to give trouble then try the following fixes in this order:

1. Inspect the archive database carefully

In Browse mode of Weatherlink (the Notepad-like icon on the toolbar or select Browse from the Window menu or simply Ctrl W) look carefully through the most recent records, especially the very last one. Look especially at the date/time values and see if you can spot one that’s patently in error (eg a date or year value that is still in the future!) or out of sequence. The commonest cause of download problems is that a spurious date/time value has somehow and, typically, recently made its way into the database. But look also for other signs of a malformed record.

When Browse mode is active, you will notice a new Browse menu appear on the main menu bar. This contains an option to delete individual records – if a spurious record is spotted then delete it. (There is also an ‘Edit’ record option, but this only allows the weather readings to be edited and not the data/time values.)

Spurious new files: A variation of this same type of issue is where a new monthly data file (see below) but from the future has been inadvertently created by the system. For instance a file called 2100-01.wlk (or something analogous with a future datastamp) can be seen in the station folder along with all the other valid .wlk files. Such files are definitely spurious and can be deleted (or, if you’re feeling cautious, renamed to eg 2100-01.wlk.old). Retrying the downloads may then reveal that the problem has been fixed.

2. Create a new station

It’s not always possible to identify faulty records through using Browse mode. But there is another approach that can be tried. In Weatherlink create a new station (File | New Station) – you do not need to work through the whole of the Walkthrough, but obviously the Communication Port step must be correctly set or the PC and logger will not be able to communicate. The main idea of a new station is just to create a test station that is previously unused and which will therefore not carry over any of the old weather readings. Try downloading the archive into that new station. If this succeeds then it’s a good sign that the latest monthly data file in the existing station is corrupt.

If a download into a new test station is fully successful then there are a couple of options for dealing with the existing corrupt data file. If your archive interval is 30 minutes or longer then the logger can hold a complete month’s worth data (and more), so you could copy the new wlk file for the current month over the top of the existing file in the old station subfolder (or perhaps just rename the old file to e.g. 2015-03.wlk.old if you prefer), in which case you should just be able to resume normal operation with the existing file. This may also be possible with shorter archive intervals in the first part of any month, but obviously if the logger no longer contains data for the first days of the month then being able to recreate the whole monthly data file from a new download will not be possible.

So with shorter archive intervals (and especially with the 1-minute interval) it will often be the case that data may be split across two distinct data files for the current month – the potentially corrupt one in the existing folder and the new one in the new station folder. Unfortunately, Weatherlink itself does not provide any tool to merge two such files and to create one single intact file. However, someone has written a utility to do this job which you can find at Please be aware that we’ve not ourselves had cause to use this utility in anger and so this is just a pointer rather than a recommendation.

3. Delete Weatherlink configuration files

If attempts to download into a new station folder do not cure the problem then it’s possible that the corruption lies in one of the configuration files that Weatherlink uses rather than in one of the monthly data files. There are two such non-essential config files that WL uses called DataLists.dat and DataSets.dat, which can both be found within the station subfolder usually located within the main Weatherlink folder. This is not the place to discuss the detailed role of these two config files, you only need to be aware of two main points:

First, these two files don’t have a major role to play in running Weatherlink – they’re present in the main to support certain supplementary functions, few of which are used routinely. However, WL does read both files and if either has a corrupt setting then this can lead to problems with archive downloads or, more typically, to issues with WL functions which read the archive data immediately after a download such as Stripcharts, Plot and Reporting functions . If you’re experiencing a problem with WL crashing shortly after an archive download then deleting these files has a good chance of fixing the fault, though it’s also worth trying with other types of download issues that haven’t been fixed by other remedies.

The second point is that if either or both of these two files is missing when WL starts up then WL will automatically recreate them using default values, which are normally fine for routine operation of WL. This means that you will not stop WL from working or interfere with its normal operation by deleting one or both of these files.

Fix: So to try this solution you can simply proceed as follows:

  1. Close the Weatherlink program;
  2. Locate the files DataLists.dat and DataSets.dat within the WL station subfolder using the Windows file manager such as My Computer;
  3. Delete one or both of these files or, if you prefer and wish to be more cautious, simply rename them e.g. by adding a .old suffix to the end of the filenames to e.g. DataLists.dat.old (which would allow recovery of the original files if required);
  4. Restart Weatherlink and retry the download;

4. Clear the logger

In the unlucky event that none of the above suggestions cures the problem then reluctantly the one last ploy that can be tried is to clear the logger.

If you do decide to clear the logger then you have two options. One approach is to use Setup | Clear | Clear Archive Memory checkbox and press OK. This seems to be a relatively recent addition to the Weatherlink user interface and, if used, it’s advisable to double-check that the logger archive definitely has been cleared.

If for any reason this option does not work then the more traditional alternative is to use the ‘Setup | Set Archive Interval’ option from the main Weatherlink menu. This is a 2-step process: you first change the archive interval away from your preferred interval. The software warns you that it is about to clear the archive memory, which you need to OK. When this step is complete you then repeat the process and change the interval back to your preferred value.

5. No solution can be found

If even clearing the logger fails to fix the problem then this could be one of the rare instances where the logger has become faulty. Please contact your dealer for support in line with the notes on support provision.

Recurrent archive download problems

If archive download issues start to happen on a recurrent or semi-regular basis then the problem clearly needs further investigation. There are, broadly, four types of cause that can interfere with archive downloads:

  • A logger that’s loose on its pins or where the USB cable is taut and repeatedly pulling on the logger so as to loosen it;
  • Where the console is run using an AC mains adapter, but the mains supply is very noisy;
  • Sources of wireless interference near to the console or USB cable;
  • Potential hard drive issues on the computer, e.g. a failing drive;

This isn’t an exhaustive list but covers the main causes. The loose logger possibility is obviously easy to check out.

A noisy AC mains supply transmits noise and spikes into the console/logger circuitry and hence can cause data corruption. The noise might arise from the AC supply at that location being inherently noisy eg in a commercial premises with heavy machinery around or at the end of a long rural supply line. Or there may be noise-generating equipment such as fluorescent lights plugged into the same electrical ring as the console adapter.

Either way, the simplest check is to completely unplug the AC mains adapter and run the console on internal battery power alone – this should completely isolate the console/logger from the mains supply. With the USB or serial loggers, the console should still run for 6-9 months on a new set of good quality batteries. (NB This won’t work for the 6555 IP logger, which does require a mains supply.) If running on batteries alone cures the problem then it might be worth investing in a small but good quality PC UPS supply (which usually provides good noise suppression ans smoothing) and running the mains adapter through that.

For ideas on investigation the wireless interference possibility see the “USB interference” topic, which can have the same cause.

If none of the above suggestions helps to cure a recurrent archive problem then the cause could well be at the computer end of the link, with a failing hard drive as a prime candidate. If possible it may be worth installing Weatherlink and trying downloads on a different PC to see if the problem is still present.(Remember that all the archive data remains unchanged on the logger until it is either overwritten or deliberately cleared. So the same data can be downloaded repeatedly to different computers.)

Last modified: Jun 04, 2021


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