Hello and tanks in advance for the help!
I needed to set up a simple temperature monitoring station, which is supposed to measure temperatures from two industrial refrigerators and log their temperatures at least hourly, and export the history of the sampled temperatures in .CSV so that I can plug the data into an Excel table under a standard formatting required for local regulations, in order to submit a monthly report.
It’s a simple task, and a fairly common application for Cayenne, but I’ve been running into some critical problems when it comes to the last step: exporting data from the Web Dashboard in csv format.
If I go into the “Data” tab within my project and select 1mo it successfully shows some of the latest measurements, loads more if I scroll down, but as soon as I click the “Download button” the page crashes and displays a default 404 error.
It’s not completely broken, though. If I try and do the same thing, only exporting the values for the last 24 hours, the web page successfully generates a .csv file and I have no problems at all.
I suspect it has to do with the way bigger size of the table, since I am requesting to download the data for the whole month?
The device works perfectly and so does the web dashboard. The graph widget logs data and accurately displays it in real time. Downloading data for the last month from the widget itself, under the “Overview” tab and not the “Data” tab works, too – but it’s not the full data for the whole month, just a set of points with daily averages, I guess.
I have only been running the project for a couple weeks. My current sketch, transmits data over two channels every 60 seconds, which is admittedly more resolution than I need for monthly reports, but having more data points is useful for short-term monitoring, and it would trigger over-temperature alarms sooner if needed, but I’ll tune it down if necessary.
The resulting table size should be, very crudely: 60 rows an hour * 24 hours a day * 30 days * ~150 characters per row… around 50 MB per channel, for a month of data?
- I’d prefer sampling at least every 10-15 minutes or so, for redundancy, so what if I tuned it down to only send only a few times an hour, would that help?
- Every row has the same DeviceID and SensorID fields, which are lengthy and useless to my specific application: is there a way to not store any to make the file lighter and more readily processed?
- What is the maximum available cloud storage provided by Cayenne, anyway? Should I expect my older data to be erased after a while, and if so how soon? Months? Years? Does it depend on storage limits?
As per the rules of the community, this is my project info:
- Device: NodeMCU ESP8266 board, connected over wifi, with two DS18B20 temperature sensors
- Dashboard: Web
- Connection: MQTT, onboard WiFi connectivity
- Sketch written in Arduino IDE using