Stations #

A Station is where you test — a physical bench with instruments. Station configs define what instruments are available and how to connect to them.

Station Configuration #

Station configs are YAML files in stations/:

# stations/bench_1.yaml
id: bench_1
name: "Production Bench 1"
location: "Lab A"
 
instruments:
  dmm:
    type: dmm
    driver: pymeasure.instruments.keysight.Keysight34461A
    resource: "TCPIP::192.168.1.100::INSTR"
 
  psu:
    type: psu
    driver: pymeasure.instruments.keysight.KeysightE36312A
    resource: "GPIB0::5::INSTR"

Instrument Configuration #

Each instrument has:

Field	Description
`type`	Instrument type (dmm, scope, psu, eload, etc.)
`resource`	VISA address or connection string
`mock_config`	Values for `--mock-instruments` mode
Instruments can be shared across multiple DUT slots in a multi-DUT fixture. When shared, the orchestrator connects them once and serves them to worker subprocesses via an `InstrumentServer` (an internal RPC server that lets multiple test workers share one physical instrument — TCP with per-resource locking). No special flags needed — sharing is detected automatically from the fixture topology. See Configuring Stations for details.

Common Instrument Types #

Type	Description	Typical Capabilities
`dmm`	Digital Multimeter	voltage (DC/AC), current, resistance
`scope`	Oscilloscope	voltage (AC), frequency, time
`psu`	DC Power Supply	voltage output, current output
`eload`	Electronic Load	current sink
`funcgen`	Function Generator	waveform output

Mock Mode #

For development without hardware, use --mock-instruments:

pytest tests/ --station=stations/bench_1.yaml --mock-instruments --dut-serial=SIM001

Configure mock values in the station:

instruments:
  dmm:
    type: dmm
    driver: pymeasure.instruments.keysight.Keysight34461A
    resource: "TCPIP::192.168.1.100::INSTR"
    mock_config:
      measure_dc_voltage: 3.31
      measure_current: 0.1

When to Use Mock Mode #

Approach	Use Case
`--mock-instruments` flag	Development, CI, station without hardware
Real hardware	Production, calibration

Station Types and Instances #

Litmus supports a two-level station architecture:

Station Types (Templates) #

Define abstract station requirements:

# stations/types/voltage_tester.yaml
id: voltage_tester
description: "Station for voltage testing"
instruments:
  dmm: {type: dmm}
  psu: {type: psu}
capabilities:                                # catalog capability ids
  - keysight.34461a.dc_voltage
  - keysight.e36312a.dc_source

One file per station type under stations/types/. Every role listed under instruments: is required (there is no required: field). capabilities: is a list of catalog capability id strings — not inline Capability dicts.

Station Instances (Deployments) #

Concrete stations that implement a type:

# stations/bench_1.yaml
id: bench_1
station_type: voltage_tester
location: "Lab A, Bench 1"
 
instruments:
  dmm:
    type: dmm
    driver: pymeasure.instruments.keysight.Keysight34461A
    resource: "TCPIP::192.168.1.100::INSTR"
  psu:
    type: psu
    driver: pymeasure.instruments.keysight.KeysightE36312A
    resource: "GPIB0::5::INSTR"

Instrument aliases per test #

Station configs define the physical instrument inventory. A sidecar YAML can optionally remap fixture names to different station instruments on a per-test or per-class basis via marker fields. See Writing Tests for details.

Using Stations in Tests #

Via pytest #

pytest tests/ --station=bench_1 --dut-serial=SN001

Via fixtures #

def test_voltage(dmm, logger):
    """Instrument roles from station config are auto-registered as fixtures."""
    logger.measure("voltage", dmm.measure_voltage())

Via CLI #

litmus serve                    # Start UI
litmus runs                     # List recent runs
litmus show <run_id>            # Show run details

Supported Test Phases #

Stations can optionally declare which test phases (test_phase is a station-level setting selecting the workflow phase — development, validation, production — and gating mocks; see how-to/profiles) they support:

id: bench_1
name: "Production Bench 1"
 
supported_phases:
  - validation
  - production
  - debug
 
instruments:
  # ...

This enables filtering when selecting stations for a given test run or profile.

Multiple Stations #

Large test environments may have multiple stations:

stations/
├── _base.yaml           # Station type definitions
├── bench_1.yaml         # Production bench 1
├── bench_2.yaml         # Production bench 2
├── debug_bench.yaml     # Debug station
└── ci_station.yaml      # CI (simulated) station

CI Station Example #

# stations/ci_station.yaml
id: ci_station
name: "CI Environment"
description: "For CI/CD with --mock-instruments"
 
instruments:
  dmm:
    type: dmm
    mock: true
    catalog_ref: generic_dmm
    mock_config:
      measure_dc_voltage: 3.3
      measure_current: 0.1
  psu:
    type: psu
    mock: true
    catalog_ref: generic_psu
    mock_config:
      measure_voltage: 5.0

Run in CI:

pytest tests/ --station=stations/ci_station.yaml --mock-instruments --dut-serial=CI-TEST

Next Steps #

Capabilities — Understanding what stations can do
Fixtures — Mapping DUT pins to instruments
Configuration Reference — YAML schema details