SPRT–NTC Calibration Logging

Parallel data logging for thermistor (NTC) calibration against an SPRT reference. Two serial instruments are read simultaneously by a small command-line logger:

• Isotech MicroK precision resistance bridge — reads the SPRT (reference thermometer).
• SchwaRTech/AWI Temperature head — reads the NTCs (and optional test channels).

Both streams are timestamped (datetime) on every line, so the two data files can be matched up afterwards purely by their wall-clock timestamps.

The calibration bath (Isotech/Fluke) is not driven yet — set its temperature setpoints manually. Automating the bath is a possible next step.

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Requirements

• macOS (serial ports are addressed as /dev/cu.*)
• Python 3
• pyserial

python3 -m pip install -r requirements.txt

If import serial fails, make sure it is pyserial (python3 -m pip install pyserial) and not the unrelated PyPI package also called serial.

Hardware / wiring

Instrument	Typical USB adapter	Baud
MicroK bridge (SPRT)	FTDI FT232R (single)	9600
SchwaRTech/AWI Temperature head	FTDI FT2232H (dual, ch0)	19200

The exact /dev/cu.usbserial-* names can change between sessions — the script lets you pick the port interactively at runtime (see below).

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Usage

Edit param_combined.txt first (see format below), then run:

python3 calibration_log.py                 # uses param_combined.txt
python3 calibration_log.py --param x.txt    # different config file
python3 calibration_log.py --exp Testlauf   # override the experiment name

At startup the script:

1. lists the detected serial ports and asks you to pick which one is the MicroK and which is the SchwaRTech/AWI Temperature head (press Enter to accept the pre-selection from the config);
2. asks for a free-text description of the calibration (until Enter) — this is stored in the _meta.txt file;
3. starts both logging threads.

Stop with Ctrl-C — both threads shut down cleanly and close their ports. Robust for long, unattended runs (e.g. inside tmux/nohup over SSH).

Live output

[MicroK] Port offen : /dev/cu.usbserial-A922BJHF
[TempLogger] Kopf ist wach.
[MicroK] #1 Ch2: <value>
[TempLogger] G1 1/63: <values>
...

Output files can be copied at any time while logging — every line is flush()ed to disk immediately, so a copy always contains all completed lines.

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Configuration — param_combined.txt

Minimal key: value format (order does not matter, # starts a comment):

experiment: Snowmelt_Retest5Sensors     # goes into the output file names

microk_channels: 1;2                     # Reference ; SPRT1 [ ; SPRT2 ]
microk_port: usbserial-A922BJHF          # optional port pre-selection

ntc_readout: NTC1;NTC2;TestSB            # from: TempADC, NTC1, NTC2, TestSB, TestN, GND, PRESSURE
ntc_groups: 5;60                         # sensors per group ; measurement points per group
ntc_nodes: 90;91;92;93;94                # sensor node IDs
ntc_port: usbserial-FT3GCNKB0            # optional port pre-selection

Key	Meaning
experiment	Experiment name, used in output file names
microk_channels	Bridge channels: Reference; SPRT1 (add ;SPRT2 for two SPRTs)
microk_port	Optional MicroK port hint (pre-selection only)
ntc_readout	Which sensor channels to log
ntc_groups	sensors_per_group ; measurement_points_per_group
ntc_nodes	Sensor node IDs
ntc_port	Optional Temperature-head port hint (pre-selection only)

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Output — three files per run, in ./Output/

<experiment>_<YYYYMMDD-HHMMSS>_microk.txt   # MicroK / SPRT data
<experiment>_<YYYYMMDD-HHMMSS>_ntc.txt      # NTC logger data
<experiment>_<YYYYMMDD-HHMMSS>_meta.txt     # resolved settings + verbatim copy of the param file

All three share the same timestamp, so one run = one matching set. The _meta.txt records the actually-chosen ports and all parameters, so the measurement settings are always recoverable later.

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Repository contents

File	Purpose
calibration_log.py	Command-line logger
param_combined.txt	Configuration
requirements.txt	Python dependencies