Electric compressor durability test-bench software: change models without rewriting code, and keep duty cycles and records fit for volume
For automotive thermal-management parts, the hard part of durability testing is not building one rig that runs. It is shipping the same software with compressors, ECUs and a string of models. Duty cycles are constant, cyclic and gradient multi-step; programmed instruments must line up with the PLC; bus frames must parse; records must stand reproduction and audit. Rewriting the HMI at every model change collapses delivery as soon as unit count rises. This article follows the layers a test-bench supervisory system actually owns: what must run unattended, which measurements a compressor rig adds, how one-off test software differs from replicable bench software, and what to lock in the specification before the next unit is copied. It describes a delivery approach already in use; it does not treat one rig's cycle time or savings as an industry rule.
Why rewriting at every model change cannot carry a volume of benches
The mechanical part of a durability bench can be copied from drawings. If the software stays a project for this serial number, the next shipment redraws screens, rewrites duty-cycle scripts and aligns instruments again. Hours follow unit count, and judgements edited on site never return to the model baseline. When an audit or a customer pulls the historical curve of one unit, configuration versions do not match and reproduction stops at a verbal account.
ORPAON delivers supervisory software for compressor and ECU durability benches to automotive thermal-management test-equipment and parts makers: automatic multi-step duty cycles, synchronised control of programmed instruments and PLCs, TDMS high-speed recording in parallel with a database channel, and CAN/LIN (including CAN FD) parsed from SDF and DBC files. Switching a model changes configuration, not code. The same platform has been delivered at a scale of dozens of units to more than one company. An English-speaking contact handles the technical window. The four splits below appear first when every bench is a one-off rewrite.
- As customers and models multiply, every switch rewrites screens and duty-cycle scripts, hours stack per unit, and versions cannot be recovered
- Constant, cyclic and gradient cyclic multi-step sequences picked by hand fail to match step boundaries in the record, so reproduction cannot align the time axis
- Programmed instruments and the PLC run on their own clocks; once they drift, the duty cycle as specified does not exist
- A single file path for records leaves holes after a break or a corrupt file, so the source curve and the stored summary disagree at audit
What must a durability-bench HMI hold at the same time?
Test-bench supervisory software is not extra mimic screens. What can be copied with the model at least puts duty-cycle execution, instrument-to-PLC sync, automotive-bus parsing, dual-channel recording and model configuration in one package. Drop one layer and the gap is invisible on the first shipment; it shows on the third unit or the next customer.
- Automatic multi-step duty cycles: constant, cyclic and gradient cyclic run from a step table, not from the operator clicking each step
- Synchronised control of programmed instruments and the PLC: temperature, pressure, speed setpoints and actuators share one time base, so the screen does not arrive before the machine
- Deep CAN/LIN parsing: LIN via SDF, CAN/CAN FD via DBC; frames enter step judgement instead of sitting as a scope bypass
- TDMS high-speed recording plus a database channel: fast waveforms go to TDMS, searchable test records go to the database, cutting holes from a single path
- Model switch changes configuration, not code: thresholds, channels, frames and the step table live in configuration; a new model does not open a new project
Which measurements does an electric-compressor bench still have to add?
An electric compressor (the automotive air-conditioning compressor, not a plant air-compressor room) under durability and aging still needs refrigerant state, airflow and liquid-slugging related signals in the same measurement-and-control set, on top of generic steps and the bus. If those items live only on a paper work instruction, judgement rules drift at a shift change or a new customer.
Several protocols have to run in parallel: Modbus RTU/TCP for instruments and the PLC, CAN/CAN FD and LIN for the unit under test, NI DAQ for analog and high-speed channels. Channel maps belong in the configuration table, not as a communications project hard-coded per rig.
- Online refrigerant properties: NIST REFPROP computes state points during the test so step judgement and the report share the same instants, instead of hand tables that miss the sample time
- Nozzle differential-pressure airflow: differential pressure and nozzle geometry enter acquisition and calculation, so airflow and compressor duty sit on one time axis
- Liquid-slugging related detection: pressure, current or vibration features that can be acquired enter the step interlock, instead of relying on an operator listening
- Safety interlocks and control boundaries: trip on limit, e-stop and the allowed command range must be definable and checked before the next unit is copied, not patched after shipment
Where does one-off test software differ from replicable bench software?
If the purchase order only says “make this unit run”, a polished screen still leaves the next unit as a project. Acceptance of replicable bench software should answer: can the next unit in the series ship from configuration, can records be searched on the same basis, and does a model change require a code change.
The table maps the contrast. The gaps come from situations that repeat on multi-customer, multi-model bench projects; they do not name an organisation.
| Item | One-off test software | Replicable bench supervisory software |
|---|---|---|
| Model change | Screens and scripts edited; code changes are routine | Configuration table and licence; no new project |
| Duty-cycle execution | Hand picks or scattered scripts | Automatic constant / cyclic / gradient multi-step |
| Record path | A single file or a single database | TDMS and database together, for reproduction and search |
| Protocol access | Only the instruments and PLC of that day | Modbus, CAN/LIN and NI DAQ configured per unit, in parallel |
| Acceptance basis | This unit finishes the specified duty today | The next unit copies by the same configuration method; versions can be traced |
What should the technical specification lock before the next unit is copied?
The steel can be copied from drawings. Software copies fail when the specification is silent. Write the four items below into the technical agreement and the next unit is not a fresh negotiation. Digital-twin development lines and travel-replacement ratios sit outside the standard delivery of this bench.
- Protocol and vehicle files: DBC, LIN SDF, the UUT frame list and byte order travel with the bench as the configuration baseline, not as a verbal promise
- Sampling and dual-channel recording: which quantities go to TDMS, which to the database, and how gaps are filled after a break, written at a grain that can be accepted
- Safety interlocks and equipment control boundaries: who issues commands, who may change setpoints, how a limit trip stops the rig — must be checkable before copy
- Model configuration table and version: channels, thresholds, step tables, licence and upgrade path; “no code change” is inspected against this table
This article describes how supervisory software for electric-compressor and similar thermal-management durability benches is delivered. The implemented scope includes multi-step duty cycles, dual TDMS and database recording, CAN/LIN parsing and configuration-based model change. Travel-replacement ratios, report-cycle figures and savings numbers not confirmed by the customer are not published. Safety interlocks and remote access follow site approval.
Summary
What lets electric-compressor durability-bench software carry volume is not a richer mimic. It is putting multi-step duty cycles, instrument-to-PLC sync, bus parsing and dual-channel recording in one configurable package, then folding refrigerant properties, airflow and liquid-slugging related measurements onto the same time base. Change the model by configuration, not by code, and the next unit can be copied.
If each bench is still its own project, you do not start by replacing every rig in the lab. Pick one model family, write the step table, frame files, dual-channel recording and interlock boundary as configuration that can be accepted, ship a few units in that family, and only then decide how far the configuration library extends.
Check whether durability-bench software can be copied by model
Tell us the UUT type (electric compressor, ECU and similar), the instruments and PLC you already have, and how many models you need to cover. We will list gaps against the step table, bus files and record channels. An English-speaking contact will handle the exchange.
Contact Us