Usage

loggertodb reads a data file (or several data files), connects to Enhydris, determines which records in the file are newer than those stored in Enhydris, and appends them. The details of its operation are specified in the configuration file specified on the command line.

Quick start

Installation

See Installation.

How to run it

First, you need to create a configuration file with a text editor such as vim, emacs, notepad, or whatever. Create such a file and name it, for example, /var/tmp/loggertodb.conf, or, on Windows, something like C:\Users\user\loggertodb.conf, with the following contents (the contents don’t matter at this stage, just copy and paste them from below):

[General]
base_url = https://openmeteo.org/
auth_token = 123456789abcdef0123456789abcdef012345678
loglevel = INFO

Then, open a command prompt and give it this command:

Unix/Linux:

loggertodb /var/tmp/loggertodb.conf

Windows:

C:\Program Files\Loggertodb\loggertodb.exe C:\Users\user\loggertodb.conf

(the details may differ; for example, in 64-bit Windows, it may be C:Program Files (x86) instead of C:Program Files.)

If you have done everything correctly, it should show an error message similar to “No stations have been specified”. This means that, apart from the “General” section you have to add more sections to the configuration file.

Authentication

loggertodb needs to logon to Enhydris, and for this it needs an authentication token to be specified as the value of the auth_token parameter. You can get a token at the /api/auth/login/ URL of Enhydris, such as https://openmeteo.org/api/auth/login/.

Configuration file examples

The following instructs loggertodb to use the single data file zeno.data and upload its data to openmeteo.org; the first field of each line (after the date and time) will be uploaded to time series group 232, the second to 233, and so on. The last field of each line will not be uploaded (symbolized with the 0). The time zone of the timestamps is 2 hours east of UTC:

[General]
loglevel = WARNING
logfile = /var/log/loggertodb/itiameteo.log
base_url = https://openmeteo.org/
auth_token = 123456789abcdef0123456789abcdef012345678

[NTUA]
station_id = 1334
path = /var/local/openmeteo/logger_data_files/ntua/zeno.data
storage_format = simple
date_format = %y/%m/%d %H:%M:%S
timezone = Etc/GMT-2
fields = 232,233,247,248,237,238,236,9141,5461,6659,9139,6661,240,6539,6541,230,234,0

The following instructs loggertodb to use two data files (one for meteorological station PRASINOS, one for VILIA; these are just labels to make it easy for you to read the file; that are not used anywhere). While reading each line’s fields, the value “NAN” instead of a number will be interpreted as an empty (or missing, or null) value. The time zone of the timestamps changes because of daylight saving time (see Daylight saving time):

[General]
loglevel = WARNING
logfile = /var/log/loggertodb/defkalion.log
base_url = https://openmeteo.org/
auth_token = 123456789abcdef0123456789abcdef012345678

[PRASINOS]
station_id = 1345
path = /var/local/openmeteo/logger_data_files/defkalion/prasino.data
storage_format = simple
date_format = %d/%m/%Y %H:%M:%S
fields = 9180,9182,9184,9178
null = NAN
timezone = Europe/Athens

[VILIA]
station_id = 1347
path = /var/local/openmeteo/logger_data_files/defkalion/vilia.data
storage_format = simple
date_format = %d/%m/%Y %H:%M:%S
fields = 9172,9174,9176,9170
null = NAN
timezone = Europe/Athens

The next is very similar to the previous one, but it’s for Windows, it uses a star for null values, and the fields in the files are delimited with commas instead of spaces. In addition, the sixth field of each line (after the date and time) is not uploaded:

[General]
loglevel = INFO
logfile = C:\a2a\loggertodb-kostilata.log
base_url = https://openmeteo.org/
auth_token = 123456789abcdef0123456789abcdef012345678

[ANO_KOSTILATA]
station_id = 1387
path = C:\a2a\ano_kostilata_20130601.txt
storage_format = simple
delimiter = ,
date_format = %d-%m-%Y %H:%M:%S
fields = 9290,9285,9292,9294,9295,0,9291,9289,9288,9286
null = *
timezone = Europe/Athens

[KATO_KOSTILATA]
station_id = 1388
path = C:\a2a\ano_kostilata_20130601.txt
storage_format = simple
delimiter = ,
date_format = %d-%m-%Y %H:%M:%S
fields = 9279,9274,9281,9283,9284,0,9280,9278,9277,9275
null = *
timezone = Europe/Athens

Finally, an example of a configuration that uses the files produced by Davis WeatherLink. In this case, C:\WeatherLink\komboti is the directory that contains the .WLK files (it is necessary to read more below about WDAT5 units and the WDAT5 format):

[General]
loglevel = INFO
logfile = C:\WeatherLink\komboti\loggertodb.log
base_url = https://openmeteo.org/
auth_token = 123456789abcdef0123456789abcdef012345678

[KOMBOTI]
station_id = 1389
path = C:\WeatherLink\komboti
storage_format = wdat5
outsideTemp = 1256
hiOutsideTemp = 1257
rain = 1652
timezone = Europe/Athens
temperature_unit = F
rain_unit = inch

Running automatically

You probably want to have loggertodb automatically update the data. To do this, either run it periodically (from cron on Unix and Task Scheduler on Windows), or, if the software you use to download the data from the meteorological station has the feature, add loggertodb as a trigger.

Command line reference

loggertodb  <configuration file> [--insert-all <station> <filepath>]

Normally loggertodb reads the last date stored in the database and then reads the input file(s) from the end upwards until it finds the date that is already stored in the database. Subsequently it enters the new records from that point on. This can be changed with the --insert-all command line option. In this case, there are the following differences from normal operation:

• loggertodb ignores all sections of the configuration file except for <station>.

• It also ignores the path in the configuration file and instead uses <filepath>.

• It also ignores max_records.

• It uploads all records in the specified file; not only those that are newer than the last record in the database. However records with these dates must not already be in the database; in this case Enhydris will refuse to upload with an http error code of 400.

--insert-all is useful when older data are discovered later and need to be inserted retroactively. It is available only for text storage formats; it is not available for wdat5.

Configuration file reference

The configuration file has the format of INI files. There is a [General] section with general parameters, and any number of other sections, which we will call “file sections”, each file section referring to one file to be processed; this makes it possible to process many files in a single loggertodb execution using a single configuration file and fewer HTTP requests.

General parameters

loglevel

Can have the values ERROR, WARNING, INFO, DEBUG, indicating the amount of output requested from loggertodb. The default is WARNING.

logfile

The full pathname of a log file. If unspecified, log messages will go to the standard error.

base_url

The base url of the Enhydris installation to connect to, such as https://openmeteo.org/.

auth_token

The token loggertodb will use to authenticate with Enhydris. Obviously the user to whom the token corresponds must have write permissions for all time series that will be uploaded.

max_records

The maximum time series length, in records, loggertodb will upload in one run. This applies individually to each uploaded time series. If there are more than this number of records to upload, only the first max_records are uploaded; the next will be uploaded in a subsequent run. This helps ease the load on the server, because attempting to upload a million records in a single request would create problems. The default is 10,000.

File parameters

station_id

The id of the station.

path

The full pathname of the data storage.

storage_format

The format of the data storage. See Supported formats.

fields

(Not for the wdat5 format.) A series of comma-separated integers representing the ids of the time series groups to which the data file fields correspond (time series groups are what Enhydris lists as “Data” in the page for a station). A zero indicates that the field is to be ignored. The first number corresponds to the first field after the date (and possibly other fixed fields depending on data file format, such as the subset identifier) and should be the id of the corresponding time series group, or zero if the field is dummy; the second number corresponds to the second field after the fixed fields, and so on.

Each time series group contains variations of the same time series, such as initial, checked and aggregated. loggertodb uploads the data to the “initial” time series of the group. If such a time series does not exist, it is created.

nfields_to_ignore

This is used only in the simple format; it’s an integer that represents a number of fields before the date and time that should be ignored. The default is zero. If, for example, the date and time are preceded by a record id, set nfields_to_ignore=1 to ignore the record id.

subset_identifiers

Some file formats mix two or more sets of measurements in the same file; for example, there may be ten-minute and hourly measurements in the same file, and for every 6 lines with ten-minute measurements there may be an additional line with hourly measurements (not necessarily the same variables). loggertodb processes only one set of lines each time. Such files have one or more additional distinguishing fields in each line, which helps to distinguish which set it is. subset_identifiers, if present, is a comma-separated list of identifiers, and will cause loggertodb to ignore lines with different subset identifiers. (Which fields are the subset identifiers depends on the data file format.)

null

Indicates how null values are represented in the source file. For example, if null = *, then a * in place of a number in the source file is interpreted as a missing value.

If the value is a number, e.g. null = -9999, then any string whose numeric value is that number will be interpreted as a missing value, e.g. -9999, -9999.00 and -9999.000000 will all be interpreted as missing values. The comparison is made with a tolerance of 1e-6.

(nullstr is a deprecated synonym of null.)

delimiter, decimal_separator, date_format

Some storage formats may be dependent upon regional settings; these formats support delimiter, decimal_separator, and date_format. date_format is specified in the same way as for strftime(3).

ignore_lines

For storage formats that are text files, it specifies a regular expression that, if it matches, the line will be ignored. This is useful to ignore header lines or otherwise lines that shouldn’t be processed.

allow_overlaps

Valid only for storage formats that are text files. If true (or yes or on or 1, and it’s case-insensitive), then overlaps are allowed. See Handling overlaps for more. The default is false.

encoding

For storage formats that are text files, it specifies the encoding. The default is utf8. List of possible encodings.

timezone

The time zone of the timestamps of the data. This is necessary to know because Enhydris stores the timestamps in UTC, so if they are in another time zone they need to be converted. The value of this parameter is a name from the Olson database (see also Wikipedia’s copy, which is handier than the official), such as Europe/Athens, but it can also be one the constant offset time zones such as Etc/GMT or Etc/GMT-2. If you use such a constant offset time zone, beware that the sign is reverted: Etc/GMT-2 is 2 hours east of UTC.

While loggertodb will handle daylight saving time, it is recommended to configure your loggers to use a constant offset time zone. See Daylight saving time for more.

temperature_unit, rain_unit, wind_speed_unit, pressure_unit, matric_potential_unit

In the wdat5 format, you can select some of the units; C or F for temperature, mm or inch for rain and evapotranspiration, m/s or mph for wind speed, hPa or inch Hg for pressure, centibar or cm (of water) for matric potential. The defaults are C, mm, m/s, hPa, centibar.

outsideTemp, hiOutsideTemp, etc.

Only for wdat5 format; see its description below.

Supported formats

Don’t create yet another conversion script

Many people think they should create a script to convert their file to a format that will be acceptable to loggertodb and then use loggertodb to read it. Don’t do that. Don’t have yet another script and yet another file—it increases the complexity of the system. If loggertodb does not support your existing file directly, contact us so that we add it (or add it yourself if you speak Python, the API is documented).

The following formats are currently supported:

simple

The simple format is lines of which the first one or two fields are the date and time and the rest of the fields hold time series values. If the first field (after stripping any double quotation marks) is more than 10 characters in length, it is considered to be a date and time; otherwise it is a date only, and the second field is considered to be the time; in this case the two fields are joined with a space to form the date/time string. The field delimiter is white space, unless the delimiter parameter is specified. The date and/or time and the values can optionally be enclosed in double quotation marks.

The format of the date and time is specified by the date_format parameter (enclosing quotation marks are removed before parsing; also if the date and time are different fields, they are joined together with a space before being parsed). If date_format is not specified, then the date and time are considered to be in ISO8601 format, optionally using a a space instead of T as the date/time separator, and ignoring any seconds. If date_format is specified, it must include a second specifier if the times contain seconds, but these seconds are actually subsequently ignored.

The values may be followed by a space and a string, which is treated as is as the flags; for example, 42.3 important flags is a value of 42.3 with flags important flags. Leading and trailing white space is stripped from the flags string.

The nfields_to_ignore parameter can be used to ignore a number of fields in the beginning of each line; this is useful in some formats where the date and time are preceeded by a record id or other field.

path can refer to many files. If it contains one of the characters *?[], it is considered to be a pattern that matches many files (glob is used for that.) It may also be a multi-line value, with one file or pattern on each line, like this:

path = /home/alice/data.txt
    /home/bob/data.txt
    /home/charlie/data.txt

When path thus refers to many files, it is assumed that their concatenation (ignoring any headers) would be the complete list of records. loggertodb does not assume the filenames are ordered in any way; it determines the order by opening all the files and reading a date from each one.

CR1000

Date and time in ISO8601, the first two fields after the date are ignored (they are a record number and a station id), and uses subset identifiers in the next field. It is not clear whether it is debugged and works properly, neither whether its features are a matter of different data logger model or different data logger configuration.

deltacom

The deltacom format is space-delimited lines of which the first field is the date and time in ISO8601 format YYYY-MM-DDTHH:mm, and the rest of the fields are either dummy or hold time series values, optionally followed by one of the four flags #, $, %, or &.

lastem

The lastem format is dependent on regional settings, and uses the delimiter, decimal_separator, and date_format parameters. It is lines delimited with the specified delimiter, of which the first three fields are the subset identifiers, the fourth is the date, and the rest are either dummy or hold time series values.

pc208w

The pc208w format is comma-delimited items in the following order: subset identifier, logger id (ignored), year, day of year, time in HHmm, measurements.

wdat5

The wdat5 format is a binary format used by Davis WeatherLink; the files have a wlk extension. When using it, set path to the directory name where your wlk files are stored (one file per month).

You can specify time serie group ids like this:

outsideTemp = 1256
hiOutsideTemp = 1257
rain = 1652

The full list of variables is outsideTemp, hiOutsideTemp, lowOutsideTemp, insideTemp, barometer, outsideHum, insideHum, rain, hiRainRate, windSpeed, hiWindSpeed, windDirection, hiWindDirection, numWindSamples, solarRad, hiSolarRad, UV, hiUV, leafTemp1, leafTemp2, leafTemp3, leafTemp4, extraRad, newSensors1, newSensors2, newSensors3, newSensors4, newSensors5, newSensors6, forecast, ET, soilTemp1, soilTemp2, soilTemp3, soilTemp4, soilTemp5, soilTemp6, soilMoisture1, soilMoisture2, soilMoisture3, soilMoisture4, soilMoisture5, soilMoisture6, leafWetness1, leafWetness2, leafWetness3, leafWetness4, extraTemp1, extraTemp2, extraTemp3, extraTemp4, extraTemp5, extraTemp6, extraTemp7, extraHum1, extraHum2, extraHum3, extraHum4, extraHum5, extraHum6, extraHum7.

Many of these fields may be reserved by Davis for future use or they may not be used in the particular installation; just don’t use them. It is also recommended to ignore the calculated values such as ET (evapotranspiration). More information about the meaning of the parameters can be found in the Davis manuals and in the WeatherLink README file.

odbc

The sane place for loggers and logger software to store meteorological data is a plain text file. Databases shouldn’t be used for that purpose. However, I’ve come across a system which was using MS Access, so I wrote this. It’s only tested on Windows and MS Access, though in theory it should be usable anywhere. In that case, path is not actually a file name but an ODBC connection string, such as DRIVER=Microsoft Access Driver (*.mdb);DBQ=C:\Somewhere\mydb.mdb. table specifies the database table in which the data is stored; each variable should be in a plain text column, and there should also be an id column indicating order. date_sql is an SQL expression that selects the date and time from the table (the resulting date and time format is defined by date_format). data_columns is a comma-separated list of (text) columns to retrieve from the table; fields must have as many entries as data_columns.

You see that this was a hack made for a specific installation, but if you are unfortunate enough to really need it, we can elaborate it further.

Daylight saving time

Important

Set your loggers to permanently use your winter time or any time that does not change.

In case this was not understood:

Set your loggers to permanently use your winter time or any time that does not change.

Loggertodb contains limited functionality to deal with cases where your loggers change time to DST. However, you should never, ever, use that functionality. Instead, you should configure your loggers to not do such an insane thing. If you use some kind of software+hardware stack that makes it necessary to configure your loggers to change to DST (something completely unnecessary, you can perfectly and easily store everything in one time zone and display it in another time zone), call your supplier and tell them they suck.

If you ignore this warning and set your loggers to use DST, don’t expect loggertodb to do miracles. It can help of course, and it might work while things work smoothly. But whenever your government changes the date or time of the DST switch, or whenever something else goes wrong, you will be trying to fix a big mess instead of doing something useful. Really, you should get a life and set your loggers to permanently use your winter time or any time that does not change.

A time series is composed of records with timestamps. If we don’t know exactly what these timestamps mean, the whole time series is meaningless. So, assuming you are in Germany, do you know exactly what 2012-10-28 02:30 means? No, you don’t, because it might mean two different things. It could mean 02:30 CEST (00:30 UTC) or 02:30 CET (01:30 UTC). (In fact, several makes of loggers discard one of the two ambiguous hours during the switch from DST, meaning that if an incredible storm occurs at that time, you will lose it. Insane but true.)

Enhydris stores all timestamps in UTC so there’s never any ambiguity and there’s no switch to DST. The timezone parameter in the loggertodb configuration file is necessary so that the timestamps are correctly converted to UTC. If you are have loggers that switch to DST and are unable to change their configuration, loggertodb can attempt to convert it for you. In that case the timezone parameter should be set to a time zone that changes to DST, like “Europe/Athens”:

timezone = Europe/Athens

loggertodb assumes that the time change occurs exactly when it is supposed to occur, not a few hours earlier or later. For the switch towards DST, things are simple. For the switch from DST to winter time, things are more complicated, because there’s an hour that appears twice. If the ambiguous hour occurs twice, loggertodb will usually do the correct thing; it will consider that the second occurence is after the switch and the first is before the switch. If according to the computer’s clock the switch hasn’t occurred yet, any references to the ambiguous hour are considered to have occurred before the switch.

Handling overlaps

Occasionally input text files may have repeated groups of lines such as this, where the second and third line are repeated:

2025-08-11 11:20,18.2,48
2025-08-11 11:30,18.3,47
2025-08-11 11:40,18.4,46
2025-08-11 11:30,18.3,47
2025-08-11 11:40,18.4,46
2025-08-11 11:50,18.5,45

Normally loggertodb will terminate with an error there and you must fix the input file. However, allow_overlaps = yes can be specified in the configuration file to change this behaviour, but it’s not without side effects.

The most significant problem is that repeated lines might have different values. In this case loggertodb will merely ignore one of the versions.

The second problem is one of performance. Normally loggertodb reads the last date stored in the database and then reads the input file(s) from the end upwards until it finds the date that is already stored in the database. Subsequently it enters the new records from that point on. This operation takes a significant time only if there are many records to be entered; for example, the first time a large file is uploaded. Otherwise the file might be 50 MB long but if only 200 bytes at the end of the file are new, only those would be read.

If allow_overlaps = yes, this way of operating does not work; there could be recent records before the first-from-the-end instance of the latest date stored in the database. Therefore, in that case, loggertodb changes its way of operating completely: it reads the entire input file(s). This may take too many resources if done frequently, so don’t run loggertodb every 10 minutes in that case.

Therefore, avoid using allow_overlaps = yes; instead, fix the input files. However, when there are too many input files and it’s not possible to assign a human to fix them, this configuration parameter could be useful.