State Logging?

The Trigger library is quite generic, as it will send a pulse or change the polarity on a Mayfly pin based on any measured value crossing any threshold. It can thus be used to control an external device, such as a latching switch (which maintains it’s state even when the Mayfly goes into low power sleep). See https://github.com/EnviroDIY/Trigger/tree/master/hardware

To use with the EnviroDIY Modular Sensors library, you must “unpack” the dataLogger.logDataAndPublish(); function in the loop, as is shown at the bottom of the menu_a_la_carte.ino example (which is commented out by default): https://github.com/EnviroDIY/ModularSensors/blob/master/examples/menu_a_la_carte/menu_a_la_carte.ino