There are times when our Festival of Trains show's Legacy system does unexpected things, but today was a first for this effect. We're running three loops with a Sensor Track on each loop set to output a crossing signal whistle sequence. Sensor cars trigger whistle signals in addition to the IR-equipped locos. Usually two Cab2 controllers are available and an iPad with the iCab app and or the HighRail app is active. I also have a PC with a program that logs Legacy commands running and sometimes the eTrain app is open. (I demo the apps to event guests).
After 5 hours running punctuated with expected crossing whistles and horns, the S.P. Daylight starts moaning constantly. Weird - this is a new one. The engine responded to Cab2 horn and dialog signals but would not shut up. My first assumption was the engine's sound board was misbehaving. A reset command stopped the moan but as soon as the engine started, the sound restarted. Power off reset didn't work either. The moaning resumed when the engine powered up. Next step was to reboot the Legacy base - it could be re-sending continuous horn commands. (I've seen bases that emit unexpected commands) No joy. The PDI cable from sensor tracks was disconnected in case one of them was sending continuous horn commands. That didn't solve the problem. The WiFi lights were still blinking wildly so one to the connected WiFi apps must be transmitting constantly. Shutting down the iPad apps and the iPad stopped the stream of commands and the Daylight stopped moaning.
The commands logged were "Quilling Horn Intensity 2" sent every ~100 milliseconds. I assign the blame to the iCab app going into a loop. The HighRail app was only used in LCS mode for Sensor Track control. A possibility is the iPad touch screen was at fault and the app was responding to stuck touch input. We'll see when we repeat this control setup tomorrow.
Lesson learned is to keep the WiFi module visible to observe the wireless activity (it was hidden behind a skirt). The wireless apps, or the hardware they run on, can be at fault and excess WiFi traffic is the clue.
