Log Data

With QPID's control algorithm now running quite nicely, I logged data during a recent rib smoking to see just how good it is. Weather conditions were cool and windy, so it was a good test for the system.

The plot shows that the actual temperature (red) stays within 2 degrees of the target temperature (blue), which is way better than I could ever hope to do adjusting the dampers by hand. The green line shows how the fan speed adjusts to maintain the desired temperature.

The yellow line shows the average fan utilization gradually increasing as the fuel is consumed. The QPID software monitors this value and sends an alert when it exceeds a preset threshold. Since I'd like a little advanced warning, I think 70% would be a good value.

Twitter Kinda Sucks

At first I was thrilled about the prospect of using Twitter to send updates. It's free, it's easy to send updates via an HTTP POST, and it handles all of the configuration for devices and following options. But there's a catch. It's really unreliable. :-(

During the course of my testing, I've noticed that I get SMS messages about 50-60% of the time, and if the message is an urgent alert about the smoker needing attention, that's just not acceptable. So, perhaps I need to add an SMTP feature to WiServer and go straight to my carrier's gateway server instead...

On the plus side, I have greatly improved the control algorithm. It makes better use of temperate changes over time to control the fan, and it also has the capability to sense when the smoker's been opened (thus avoiding false alarms for a low fire).