Quick start#

Launch the rack application#

The qinstrument command launches a rack that holds multiple instrument widgets. Pass instrument names as arguments:

qinstrument DS345 SR830

With no arguments, the rack restores the last-used instrument list from ~/.QInstrument/QInstrumentRack.json:

qinstrument

You can also use python -m QInstrument in place of qinstrument.

At runtime, click Add instrument… to load an instrument from the list of available drivers, or right-click any instrument panel to remove it. The rack saves its instrument list on close and restores it on next launch.

Use a simulated instrument#

When hardware is not available, pass a fake device directly:

from qtpy.QtWidgets import QApplication
from QInstrument.instruments.StanfordResearch.DS345 import QDS345Widget, QFakeDS345

app = QApplication([])
widget = QDS345Widget(device=QFakeDS345())
widget.show()
app.exec()

Access instrument properties programmatically#

from QInstrument.instruments.StanfordResearch.DS345 import QDS345

ds345 = QDS345().find()
if ds345.isOpen():
    print(ds345.get('frequency'))
    ds345.set('frequency', 1000.0)
    ds345.close()

Use a parameter tree#

Each instrument also ships a QInstrumentTree that presents all registered properties and methods in a pyqtgraph.parametertree.ParameterTree — no .ui file required. Install the optional dependency first:

pip install 'QInstrument[tree]'

Then use the tree the same way as the widget:

from qtpy.QtWidgets import QApplication
from QInstrument.instruments.StanfordResearch.DS345 import QDS345Tree

app = QApplication([])
tree = QDS345Tree()
tree.show()
app.exec()

Run a single tree from the command line:

python -m QInstrument.instruments.StanfordResearch.DS345.tree

The tree reflects live device changes (e.g. from a polling timer) and forwards user edits to the device. Read-only properties are displayed but cannot be edited; registered methods appear as buttons.

Show a subset of properties and methods#

By default the tree displays every registered property and method. To restrict the display, pass a fields list at instantiation time:

tree = QDS345Tree(fields=['frequency', 'amplitude', 'function'])

The names must match those used in registerProperty() / registerMethod(). The display order follows the list.

For a permanent per-class subset, declare FIELDS on the subclass:

class QDS345Tree(QInstrumentTree):
    INSTRUMENT = QDS345
    FIELDS = ['frequency', 'amplitude', 'function']

If any name in fields or FIELDS does not match a registered property or method, a warning is logged and the full set of properties and methods is shown instead so the instrument remains usable.

Rate-limit sensitive properties#

Some instruments cannot accept rapid-fire changes — a laser power control, for example, should not be updated many times per second as the user scrolls a spinbox. Declare a debounce interval (milliseconds) when registering such a property and QInstrumentWidget will coalesce rapid UI changes automatically, sending only the final value to the device once the user pauses:

self.registerProperty(
    'power',
    getter=self._get_power,
    setter=self._set_power,
    ptype=float,
    minimum=0., maximum=100.,
    debounce=500          # wait 500 ms after the last change
)

No widget code is required. Properties without debounce (or with debounce=0) continue to update the device on every signal emission, as before.