THUNDERMILL02 Raw Data Format
Table of contents
This page describes the data stream sent by the sensor. You need it when using the sensor without the terminal, e.g. connected directly to a computer or a data logger. For the data stored by the terminal, see Data Storage and Access.
The sensor sends its data as a one-way ASCII stream over the RS485 interface (115200 baud, 8 data bits, no parity, 1 stop bit). Each message is one line terminated by a newline. Lines starting with # are informational messages (e.g. at startup) and carry no data.
Identification Header
After power-up, the sensor sends an identification header once, before the data stream:
$MILL,THUNDERMILL02,1.0.0-0-CIBuild,0,e8231d3c2643d1be2363cf65275ef62ede0742f1,<serial number>
$ADC,USTEFMADC01B,<serial number>,ffff
| Field | Example | Description |
|---|---|---|
$MILL | Message identifier | |
| Model | THUNDERMILL02 | Sensor model |
| Firmware version | 1.0.0-0-CIBuild | <major>.<minor>.<release>-<build>-<build type> |
| — | 0 | |
| Git hash | e8231d3c… | Firmware source revision |
| Serial number | 32 hex digits | Unique serial number of the sensor |
The $ADC line identifies the analog front-end board (model, serial number).
Waveform Message
The main message carries the signal measured during one revolution of the rotor:
32768,32801,32915,…,32790
- Comma-separated raw ADC values (16-bit unsigned, 0–65535, printed as 5 digits with leading zeros). The value 32768 corresponds to zero signal.
- The line is terminated by the rotor revolution pulse, so one line = one rotor revolution. The number of samples per line depends on the rotor speed (typically ~100).
- The electric field intensity is calculated by the terminal from the waveform (difference of the samples at the exposed and shielded rotor positions, multiplied by a calibration constant).
Environment Message
Every 10 seconds, the sensor reports the temperature and relative humidity measured inside the sensor housing. The message is sent between two waveform lines:
$ENV,,1234.56,21.4,55.2
| Field | Example | Description |
|---|---|---|
$ENV | Message identifier | |
| — | (empty) | Reserved field |
| Time | 1234.56 | Time since sensor power-up in seconds (10 ms resolution) |
| Temperature | 21.4 | Temperature in °C |
| Humidity | 55.2 | Relative humidity in % |