fefluxgate

A MIDAS frontend for the orange TRIUMF fluxgate magnetometer DAQ box.

Overview

The frontend connects to the DAQ box over ZMQ, continuously polls the streamed magnetometer data in a background thread, and publishes it into MIDAS as a periodic equipment. Every second it writes the latest reading of all 16 magnetometers into a single FG00 bank. Acquisition parameters (rate, filtering, which magnetometers to read, etc.) are set live through the ODB.

Files

File	Purpose
fefluxgate.py	MIDAS frontend; defines the FluxGate periodic equipment and ODB settings.
FluxgateBox.py	ZMQ interface to the DAQ box (background polling + register read/write).
start_fefluxgate.sh	Environment setup and launch script.

Requirements

• MIDAS with its Python bindings (midas.frontend, midas.event)
• pyzmq
• numpy

Running

./start_fefluxgate.sh

The script sets MIDASSYS/PYTHONPATH, activates a Python virtual environment, and runs python3 fefluxgate.py. Paths in the script are hard-coded for the UCN DAQ host — adjust them for your environment. With MIDAS already configured you can also run python3 fefluxgate.py directly.

Configuration

Settings live under /Equipment/FluxGate/Settings in the ODB and are applied immediately when changed (invalid values are rejected with a message and reset to a safe default).

Setting	Default	Allowed values	Description
host_ip	142.90.151.5	—	IP address of the DAQ box.
rate	0	0–22	ADC sample rate; 0 is fastest.
settle_delay	0	0–7	Settling delay.
enhanced_filter	0	0, 2, 3, 5, 6	Enhanced filter mode (0 disables it).
use_sinc3	False	True/False	Use sinc3 filter (ignored when the enhanced filter is on).
use_magnetometer	0xffff	0x0000–0xFFFF	Bitmask of enabled magnetometers (bit 0 = Mag 1 … bit 15 = Mag 16).
poll_ms	10	—	Interval between ZMQ polls of the box, in milliseconds.

Data format

The FG00 bank (event id 2323, SYSTEM buffer) contains 48 floats: magnetometers 1–16, each as an (x, y, z) triple. Values are converted from the 24-bit bipolar ADC codes to volts by raw_to_voltage in FluxgateBox.py (internal 2.5 V reference).