TA Instruments TRIOS .tri

TRIOS 5 writes the data of TA Instruments DSC, TGA and DMA analyzers and Discovery rheometers as .tri files. OpenReadout returns every procedure step with its stored signals, the instrument and sample facts, and for parallel-plate oscillation steps the moduli TRIOS computes. Files of TRIOS 3 and 4 are refused.

Derived from public TRIOS 5.1 to 5.9 files of several Zenodo depositors (Discovery HR-2 and HR30, DSC25, DSC2500, TGA550, DMA850), compared with TRIOS’s own exports where the depositor published them. Provenance: docs/provenance/ta-trios.md. Crate: openreadout-thermal.

format id	files	reads	confidence
ta-trios	.tri files written by TRIOS 5 (DSC, TGA, DMA, Discovery rheometers)	every procedure step with its stored signals; the instrument, serial, TRIOS version, operator, sample, procedure and geometry; for parallel-plate oscillation steps the storage and loss moduli, tan δ and complex viscosity TRIOS computes	generated (book/src/reference/evidence.md)

Not read: files of the 2019 generation (TRIOS 3/4; byte 2 = 0C), whose steps hold no signal records of this layout — refused with exit 6 and a hint to export from TRIOS; variables TRIOS computes and does not store (normalised heat flow, derivatives, viscosities of flow steps, DMA moduli, the moduli of other geometries); per-point oscillation waveforms; analysis results (fits, peak integrations) stored in the file.

Layout

part	content	our reading
bytes 0-24	00 25, a generation byte (0E), a size, 08 25 02, …, 14 20 01, u32 header length, u32 entry count	generation → format_version
header	entry count × (key, value) of 7-bit-length UTF-8 strings: instrumenttype, instrumentserialnumber, instrumentname, companyname, rundate, culture, ticks (.NET ticks of the PC clock), holder (geometry), operator, project, samplename, comments, procedurename, proceduresegments (; or #), proceduresignals, instrumentmode, testtype, samplesize	vendor tree trios; experiment facts
thumbnail	01 00 01, u32 length, a PNG	skipped
objects	21 06 <u32 length> <GUID>; a procedure step’s payload starts with 16 zero bytes and F2 21 01 04 00 00 00 00 00 00 00 01 00 11 20 02 and contains its properties and signals	one trace per step with signals
properties	20 04 <u32 length> <key GUID> …, 06 20 01 <u32 length> <u32 type> <u32 1> <value> (type 2 float64, 4 string)	step name (key d467abca-…), TRIOS version (ed6fea85-…), the moduli constants below
signal	21 06 <u32 length> <signal GUID> 01000000 01000000 00 F2 21 01 04000000 00000000 01 00 <u32 n> 01 10 21 01 <u32 L> <L bytes> 01 00 <u32 n> n × float32, then 3 bytes	a channel; the L-byte block is a zero (L = 4) or n per-point u32 flags (extra.flagged_points counts the non-zero ones)
other 21 06 records	second u32 0x02800001: a variable TRIOS computes (no values); 0x101: the step’s signals again with n + 1 points and no values; first u32 2: 64 values per point (oscillation waveforms)	left out (assurance.undecoded)

Each step’s signal GUID is global: the same quantity has the same GUID in every file and instrument. Values are SI (time s, heat flow W, weight kg, torque N·m, angles rad, gap m) except temperature (°C).

Channels (our vocabulary)

The first channel is the step’s time axis: time when stored (DSC, TGA), else step_time (rheometers), else the point index (extra.axis.quantity = point). Channels keep the stored order after it. extra.label is TRIOS’s name, extra.guid the signal GUID.

name	TRIOS label	unit	how it was named
time	Time	s	proceduresignals position (DSC, TGA); DSC/TGA exports
temperature	Temperature	°C	every export
heat_flow	Heat Flow	W	DSC proceduresignals; = −(exported Heat Flow (Normalized)) × sample size (the files’ display setting is Exo Up)
delta_t, delta_t_zero, t_zero_temperature, cell_purge, heater_temperature, power_delivered, reference_junction_temperature, flange_temperature, heat_flow_phase, total_heat_capacity	Delta T, Delta Tzero, Tzero Temperature, Cell Purge, Heater Temp, Power Delivered, Reference Junction Temperature, Flange Temperature, Heat Flow Phase, Total Heat Capacity	°C for the temperatures, else none	DSC25 proceduresignals (13 names for 13 records), the same GUIDs in the same positions in the DSC2500 file
heat_capacity	Heat Capacity	none	DSC2500 proceduresignals (14 names for 14 records)
weight	Weight	kg	TGA proceduresignals; TGA export (mg)
temperature_difference, sample_purge, balance_purge, set_point_temperature, ramp_rate	Temperature Difference, Sample Purge, Balance Purge, Set Point Temperature, Ramp Rate	°C for the set point, else none	TGA550 proceduresignals positions (9 names, 10 records; the tenth is unnamed)
angular_frequency	Angular frequency	rad/s	rheometer exports (30 of 30)
step_time	Step time	s	rheometer exports
raw_phase	Raw phase	rad	rheometer exports (in °)
oscillation_torque	Oscillation torque	N·m	rheometer exports (in µN·m)
oscillation_displacement	Oscillation displacement	rad	rheometer exports
gap	Gap	m	the moduli (TRIOS’s strain constant needs it)
signal_<first 8 hex of the GUID>	—	none	unknown meaning
storage_modulus, loss_modulus, tan_delta, complex_viscosity	Storage modulus, Loss modulus, Tan(delta), Complex viscosity	Pa, Pa, –, Pa·s	computed (below); extra.computed says so

Oscillation moduli (computed)

For steps with angular frequency ω, torque M, raw phase φ, displacement θ and gap h, when the holder names a parallel plate and the file stores the geometry’s stress constant K_τ (e4fea4e5-…, 2/(πR³)), the instrument inertia (6594d858-…), the geometry inertia (2dad9ebd-…) and the sample density ρ (a58eb6fe-…):

• R = (2 / (π K_τ))^(1/3), strain constant K_γ = R / h;
• I = instrument inertia + geometry inertia + π ρ h R⁴ / 6 (the sample);
• G′ = K_τ (M cos φ + I ω² θ) / (K_γ θ), G″ = K_τ M sin φ / (K_γ θ), tan δ = G″ / G′, |η*| = √(G′² + G″²) / ω.

These are TRIOS’s numbers: in 30 of 30 exports of one depositor (three sessions with different inertia calibrations, a 12 mm plate) within 2e-5 relative in time sweeps and 4e-4 in frequency sweeps (at 628 rad/s the inertia term cancels 99 % of the torque, and the stored float32 values limit the difference). Other plate diameters are computed the same way but never compared: the assurance feature oscillation moduli, parallel plate <d> mm says which.

Validation

cargo test -p openreadout-corpus-tests --features corpus (tests/series_oracle/mod.rs, oracle/series_oracle.py --trios-export): every column TRIOS exported whose label a channel shares is compared row by row (sampled at up to 256 rows): rheometer exports to the export’s 6 significant digits (stored signals) and 1e-3 relative (moduli), DSC time, temperature and heat flow to the CSV’s rounding, TGA time, temperature and weight to the workbook’s rounding; the operator and sample name of the rheometer exports’ Details sheet.

Vocabulary (public API of openreadout-thermal, TRIOS)

identifier	meaning
TriosReader	reader of TA Instruments TRIOS .tri files
TRIOS_FORMAT_ID	ta-trios

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How this reader was derived, file by file: provenance log.