DALI · API access

Data downloads

What you get when you download data from a station. The ZIP and file names, the CSV columns, the time zone, how missing values appear, and the SD card archive.

Anyone who can sign in to a station, Users included, can download its data from the Data Download tab of the Data output page. This page describes exactly what the files contain. For the steps, see Download data.

What you can download

Button	What it contains
Download Logged Data	Logged data: one record per logging interval
Download Raw Data	Raw data: readings every 1 to 30 seconds, each with a Valid flag. Only there if raw logging is turned on under Device, Storage.
Download SD Raw Data, Download SD Logged Data	The same two kinds, read from the station's SD card archive. See The SD card.
Download GPS Health Log	GPS diagnostics, for Aeron staff (Factory role) only

Pick a From and To date and time (the time is HH:MM, in station time) and click the button. The SD card form takes dates only. The station may start preparing the download as soon as you pick the dates, and shows Ready to download when it has. A large download can open a new browser tab that shows progress.

A station prepares one download at a time. If someone else is downloading, yours waits, and after two minutes you see "Another download is in progress on this device. Please try again shortly."

File names

You get one ZIP file:

Download	ZIP name
Logged data	`Logged_DataFiles_<date>_T_<time>.zip`
Raw data	`Raw_DataFiles_<date>_T_<time>.zip`
SD logged data	`SD_Logged_DataFiles_<date>_T_<time>.zip`
SD raw data	`SD_Raw_DataFiles_<date>_T_<time>.zip`

The date and time in the ZIP name record when the download was made, for example Logged_DataFiles_2026-09-28_T_10_15_42.zip. Use the file names inside to see what period the data covers.

Inside the ZIP there is one CSV file per data file on the station. How much time each file covers is the Create Interval set under Device, Storage (1, 3, 6 or 12 hours, 1 day, or for logged data 1 month). Each CSV is named after its first record, as DDMmmYYYY_HHMMSS.csv:

28Sep2026_000000.csv
28Sep2026_010000.csv
28Sep2026_020000.csv

If two files would get the same name, the second gets _1, the next _2, and so on. A new file also starts wherever the station's clock jumped or its time zone changed, so you may see a file that starts at an odd time.

Every CSV has its own header row, so each file can be opened on its own.

Columns

Logged data

Device Date,Device Time[<serial number>],Latitude,Longitude,GPS Fix,GHI (W/m2),Module Temp (degC)
2026-09-28,10:15:00,28.613900,77.209000,1,812.4,41.25

Column	Contents
Device Date	`YYYY-MM-DD`, station local date
Device Time[serial number]	`HH:MM:SS`, station local time. The header carries the station's serial number, so a file always says which station it came from.
Latitude, Longitude	Degrees, 6 decimal places
GPS Fix	The GPS fix status reported by the GPS, as a whole number
One column per parameter	Header is `Name (Unit)`. Columns are in parameter order, as set on the Parameters page.

Raw data

Raw data has the same first five columns. After each parameter's value comes a Valid column:

Device Date,Device Time[<serial number>],Latitude,Longitude,GPS Fix,GHI (W/m2),GHI Valid,Module Temp (degC),Module Temp Valid
2026-09-28,10:15:01,28.613900,77.209000,1,812.4,1,41.25,1

Valid	Meaning
1	Fresh: read from the sensor for this record
0	Held: the last good value, between reads
2	Stale: the sensor has stopped answering
3	Never received: the sensor has not answered since the station started

How values are written

Each value is rounded to the number of decimals set for its parameter.
A whole number is written without a decimal point: 0, not 0.00.
A parameter that holds a time of day is written as HH:MM.
A stale or never received value is written as nan, so it cannot be mistaken for a real reading of zero. If the software reading your files cannot handle nan, switch Device, Storage, Stale Value Representation off to write 0 instead. The switch changes downloads, cloud uploads and Modbus together.
Rows that appear twice (for example after a restart) are removed.

Time zone

Dates and times are the station's local time, with no offset column. Each record keeps the time zone that was in effect when it was recorded, so changing the station's time zone later does not shift old records. If you combine files from stations in different time zones, convert them yourself. Keep the station's clock correct: see Set the time.

The SD card

Stations with an SD card slot keep a long-term archive on the card as well as on internal storage. The SD Card Data Download section appears on stations that have a slot, and tells you its state:

Message	Meaning
SD card disabled by administrator	An Admin has switched the SD card off under Device, Storage.
SD card not mounted	No card is fitted, or the station cannot read it.
SD card mounted, no data files found	The card is working but holds no data yet.

Files on the card are encrypted. You cannot read them by taking the card out and putting it in a computer. Download them through the console, which decrypts them for you. The CSV layout and file names are the same as above.

USB drive

A station can also copy plain CSV files to a USB drive plugged into it. This is off unless an Admin turns on Enable USB data export under Device, Storage, and every change to that switch is recorded in the activity log. See Device.