Tag Archives: data logger

How to use the OpenKontrolGateway for Data Logging

The obvious place to look is this post, OpenKontrol Gateway as Data Logger from openmicros.org, which has some sample code, which didn’t work for me. It created the log file but didn’t write any data to it.

I hacked this to make it write the data

unixtime,day/month/year hour:minutes:seconds, LLAPmessage
1352219944,6/11/2012,16:39:4,ECTMPA7.866
1352219992,6/11/2012,16:39:52,EATMPA21.59
1352220052,6/11/2012,16:40:52,EBTMPA20.82

It’s also a bit more tricky to use, compared to a regular data logger. This is because the RF network is unsynchronised – the temperature nodes fire themselves up every 5 minutes, transmit a temperature reading and then go to sleep. This isn’t a polled system, and there may be other transactions on the network. The data logger simply logs all of these transactions, be they temperature readings, status readings or setting up devices – anything starting with an a is logged.

This is why I added the unix timestamp, so that it would be possible to plot these unsynchronised elements onto the same xy plot, with the timestamp along the x axis. Some data might want to be sampled more frequently than every 5 minutes, and some might be reactive, like a PIR sensor.

The receiving application has to pull all this stuff apart, first splitting the streams into the devices, using LEFT(LLAPmessage,3). This will always be aXY with XY being the deviceID

 

Modified program shown below

Continue reading