#Sensor
Reading an Unknown Modbus Device: Verify Before Interpreting
My notes on tracking down an undocumented device on an RS485 bus, from scanning baud rates and addresses one combination at a time to proving which registers hold live values and which are dead, and the lesson that guessing a device's type from number patterns alone can lead to months of misinterpretation.
Inferring Cold Room Defrost Timing from Temperature Slopes
A cold room used to dehydrate glass noodles has no humidity sensors, but frost on the coil always flattens the temperature drop slope (dT/dt). This article uses the lumped-capacitance equation and time constant τ to detect frost and trigger demand defrost with working Python code, along with calculations for R404A COP and water removed per cycle.
Reading Modbus RTU over an RS485 Gateway Without Phantom Values
Connecting multiple Modbus RTU meters/sensors on an RS485 bus through a serial-to-Ethernet gateway can produce phantom values, incorrect readings, or devices that do not actually exist — because a transparent gateway uses RTU-over-TCP, which requires assembling frames and calculating CRC yourself, and validating every reply. This article covers the rules I learned from doing it.