Below we’ve collected tips & tricks on the WiFi transfer based on user experiences:
Table of Contents
We strongly recommend that you familiarize yourself with the CANedge2 before you deploy it in the field. In particular, make sure to test your configuration (see also below points) and ensure that you get familiar with over-the-air updates of configuration and firmware.
Once you’ve verified that you can upload data to your server, you can optionally enable HTTPS.
The amount of data logged by the CANedge2 can differ dramatically. In most applications the unfiltered log rate will be about 0.5-1.5 MB/minute.
The upload rate will also differ, e.g. based on coverage/stability of your WiFi access point. Further, you may have a use case where data is only offloaded every 3rd day in an interval of 20 minutes. In these latter cases, it’s extra important to determine the amount of data logged between each of these intervals - and evaluate the amount of data uploaded per minute with your access point.
Based on evaluations, you can tweak your filters, prescaling, compression, control signals etc. to optimize your data. Also consider if adding WiFi access points can increase upload intervals.
The CANedge2 does not (yet) support resumable file uploads. This means that if a large file transfer fails, the device will have to start from scratch. In use cases with constant and stable connectivity this is typically not an issue. However, if data is uploaded periodically (e.g. when a vehicle returns to a specific area), it is recommended to use a small split size - e.g. 5 MB.
On the other hand, we do not recommend to use e.g. 10-30s split sizes. While it enables “near real-time upload” it will cause large overheads on your data and post processing will be less efficient. If you’re using a cloud server, it’ll also cause your PUT API request costs to increase.
We recommend to encrypt your passwords before deploying the unit in the field. Without this, others can access your WiFi/server by extracting your device SD card. However, make sure to test your connection with the encryption enabled to ensure you performed the change correctly.
For batch encryption we recommend using the OTA batch manager tool.
It’s generally useful to monitor your device status via the CANcloud status dashboard, e.g. to watch out for bottlenecks, unexpected delays in your device heartbeats or issues with declining SD card capacity (indiciating an issue with your log rate vs. upload rate).
Using over-the-air updates can be a bit confusing at first. In particular, note that once your CANedge2 has connected to your server, it will upload the Configuration File to the device folder. If you then manually update the Configuration File on the SD card of the device, you’ll experience that the changes you made get overwritten. This is because the CANedge2 recognizes that there is a different Configuration File on your server - which triggers an over-the-air update. In other words this is working as intended - but may be confusing the first time.
Over-the-air updates are powerful, but they should be used carefully. Performing an update can lead to the CANedge2 getting disconnected from your server, e.g. if you tweak a setting without knowing the full extent of what effect this has.
In particular, be careful in changing the following settings over-the-air:
- Real-time clock: The device requires that the RTC is synced at all times to communicate with your server. Therefore we strongly recommend to keep the WiFi RTC sync enabled at all time and avoid modifying the RTC Adjustment field
- Split size: Changing the split size to a large file size can cause a block of the data upload if you e.g. have an unstable connection as explained further above.
- 2nd port: If your device is uploading data via a hotspot powered through the 2nd port, it’s important that you do not turn this off via a configuration change
- Connect: Most of the
connectsection is sensitive. Fully understand each field before changing anything. For details, hover fields in CANcloud or review the field in the CANedge Docs