REXDESK: send decoded snapshot files to S3

Send a small JSON file of live decoded values to your S3 bucket at a set interval, alongside the full logs. The values can be GNSS position or engine signals, for example.

What a snapshot file is

A snapshot file is a JSON file holding the latest decoded value of a few signals you choose. The logger samples the signals at the rate you set. It uploads the file to your bucket at a separate interval. A dashboard or script can then read current values without converting a full log. The complete logs still upload as usual.

Snapshot files work on REXGEN Air.

Create a snapshot file

1. Add the Snapshot tool. Drag Snapshot from the Transmitting group in the Tools panel into Output in the Configuration panel. The Snapshots window opens.

   

2. Add a file. Select Add Snapshot File.
3. Name the file and set the rates. Enter a Name, the Sampling Rate (sec) and the Upload Rate (sec), then select OK.

   

The Snapshots window toolbar also has Remove Snapshot File. Add Items and Remove Items change the items in the selected file.

Add items

Signals from a DBC file

1. Open the signal list. Select the snapshot file, then Add Items > Add Signals.
2. Choose the signals. Tick the signals you want from a DBC file already in the library. To use another DBC file, select the folder button. Then select OK.
3. Set the bus. For each signal, select the CAN channel it comes from in the SourceCan column.

Internal channels

Select Add Items > Add Internal Channels to add the logger's own data. Tick the channels you want and select OK. The internal channels are:

• GNSS timestamp, date and time
• Longitude, latitude and altitude
• Speed and course over ground
• Fix quality and number of satellites
• Geoid separation and ground distance
• The analogue inputs ADC 0 and ADC 1

Send the configuration and read the file

1. Send the configuration. Select Run. The logger starts uploading snapshot files to the bucket as soon as it runs the new configuration.
2. Find the file. Open the logger's root folder in your bucket. The folder is named after the logger's serial number. The snapshot file is there as a .json file.
3. Read the values. The values in the file update at every upload.

A snapshot with GNSS channels and one DBC signal looks like this (example values):

{
"RTC_UNIX":1770400000,
"GMT_UNIX":1770400000,
"LATITUDE":52.000000,
"LONGITUDE":-0.400000,
"ALTITUDE":60.000000,
"SPEED_OVER_GROUND":0.000000,
"GROUND_DISTANCE":100.000000,
"QUALITY":3.000000,
"EngTotalHoursOfOperation":390.000000
}

Next: REXDESK: activate a licence and encrypt logs.