Internal Storage

Some PalmSens devices have an internal filesystem where they can store measurements (.dmeas files), and other data, e.g. generated by MethodSCRIPT. PyPalmSens provides a file-system-like interface to browse, read, write, and delete files on the connected instrument through pypalmsens.DeviceFileSystem. Asynchronous workflows are supported via pypalmsens.DeviceFileSystemAsync.

Devices that support storage (check your device manual):

PalmSens 4
EmStat 4
EmStat Pico
Sensit Wearable
Nexus

Saving data to your device

For a start, these are three ways to save measurement data to the device:

PSTrace: Click the 'Save on internal storage' checkbox before running a measurement
PyPalmSens: Set the save_on_internal_storage flag on a method:

import pypalmsens as ps

method = ps.LinearSweepVoltammetry(general={'save_on_internal_storage':True}
ps.measure(method)

MethodSCRIPT: See the documentation here for various ways of saving data to files (not limited to measurement data)

Connecting to the filesystem

To access the device filesystem you need an active connection to the instrument. If you already have an active connection, you can pass an instance of pypalmsens.InstrumentManager (or its async counterpart) directly:

>>> import pypalmsens as ps

>>> with ps.connect() as manager:
...     fs = ps.DeviceFileSystem(manager)
...     print(fs.listdir())
[DevicePath('Measurements/17-07-2026/LSV-10-00-25-0.dmeas'),
 DevicePath('Measurements/17-07-2026/LSV-10-00-28-1.dmeas'),
 # ...
 DevicePath('Measurements/16-07-2026/CV-14-46-50-2.dmeas')]

DeviceFileSystem supports the context manager protocol, so you can pass a pypalmsens.Instrument instance. In this case, DeviceFileSystem internally creates a new manager, and manages the connection:

>>> instrument = ps.discover()[0]
>>> with ps.DeviceFileSystem(instrument) as fs:
...     # filesystem operations

Browsing files

Use pypalmsens.DeviceFileSystem.listdir to list or pypalmsens.DeviceFileSystem.iterdir to generate entries in a directory on the device. By default, they list the contents of the root directory:

>>> fs = ps.DeviceFileSystem(manager)
>>> for path in fs.iterdir():
...     print(path)
DevicePath('Measurements/17-07-2026/LSV-10-00-25-0.dmeas')
DevicePath('Measurements/17-07-2026/LSV-10-00-28-1.dmeas')
DevicePath('Measurements/16-07-2026/CV-13-06-33-0.dmeas')
# ...

Note that there are two different implemantations. Some devices, like EmStat 4 in the example above recursively list all files. Other devices, like PalmSens 4, only list the entries in the current directory, requiring a few more steps to drill down to the measurement files:

>>> fs = ps.DeviceFileSystem(manager)
>>> fs.listdir()
[DevicePath('Measurements')]

>>> fs.listdir('Measurements')
[DevicePath('Measurements/06-01-2025'),
 DevicePath('Measurements/23-06-2025'),
 # ...
 DevicePath('Measurements/20-07-2026')]

>>> fs.listdir('Measurements/20-07-2026')
[DevicePath('Measurements/20-07-2026/CV-11-46-28-0.dmeas'),
 DevicePath('Measurements/20-07-2026/CV-11-46-35-1.dmeas'),
 DevicePath('Measurements/20-07-2026/CV-11-46-41-2.dmeas')]

pypalmsens.DeviceFileSystem.walk walks the directory structure and generates filenames sarting from a device directory. The interface is consistent for all devices:

>>> with ps.connect() as manager:
...     fs = ps.DeviceFileSystem(manager)
...     for path in fs.walk():
...         print(path)
'Measurements/23-06-2025/CP-15-54-39-0.dmeas'
'Measurements/20-07-2026/CV-11-46-28-0.dmeas'
'Measurements/20-07-2026/CV-11-46-35-1.dmeas'
'Measurements/20-07-2026/CV-11-46-41-2.dmeas'

Path handling

PyPalmSens uses pypalmsens.DevicePath objects for all path operations. Each of the methods above return instances of DevicePath. DevicePath is a subclass of Python's pathlib.PurePath with POSIX-style semantics, so you can use familiar path operations:

>>> fs / 'Measurements' / '17-07-2026' / 'LSV-10-00-25-0.dmeas'  # (1)!
DevicePath('Measurements/17-07-2026/LSV-10-00-25-0.dmeas')

The / operator is overloaded on the filesystem instance to join paths.

You can use standard pathlib.PurePath methods:

>>> path = fs.root / 'Measurements' / '17-07-2026' / 'LSV-10-00-25-0.dmeas'
>>> path.name
'LSV-10-00-25-0.dmeas'
>>> path.parent
DevicePath('Measurements/17-07-2026')
>>> path.suffix
'.dmeas'

For more information, see the pathlib.PurePath documentation.

Loading Measurements

The most common use case for the device filesystem is loading saved measurements. Use pypalmsens.DeviceFileSystem.load_measurement to load a .dmeas file from the device into a [pypalmsans.data.Measurement][] object:

>>> import pypalmsens as ps

>>> instrument = ps.discover()[0]

>>> with ps.DeviceFileSystem(instrument) as fs:
...     path = 'Measurements/17-07-2026/LSV-10-00-25-0.dmeas'
...     measurement = fs.load_measurement(path)
>>> measurement.curves
[Curve(title=LSV i vs E, n_points=11)]

Reading text files

For plain-text files on the device (such as custom MethodSCRIPT output), use pypalmsens.DeviceFileSystem.read_text:

>>> content = fs.read_text('measurement0000.txt')
>>> content
'v01.09.00\nPba7FBF3B9f,14,20C,44\n\n'

Removing files

Use pypalmsens.DeviceFileSystem.remove to delete a file from the device:

>>> fs.remove('Measurements/17-07-2026/LSV-10-00-25-0.dmeas')

Deleting all files

To clear all files on the device, use pypalmsens.DeviceFileSystem.delete_all_files:

>>> fs.delete_all_files(confirm=True)  # (1)!

The confirm flag defaults to False as a safety measure in interactive environments like Jupyter notebooks or REPL sessions. Set it to True to delete all files.

Checking if files exist

Use pypalmsens.DeviceFileSystem.exists to check whether a path exists on the device:

>>> fs.exists('Measurements/17-07-2026/LSV-10-00-25-0.dmeas')
True
>>> fs.exists('Measurements/missing_file.dmeas')
False

File metadata

You can query file metadata:

>>> path = 'Measurements/17-07-2026/LSV-10-00-25-0.dmeas'
>>> fs.size_of(path)
3764  # bytes
>>> fs.timestamp_of(path)
'2025-11-15T14:32:00'  # ISO format string

Note that this loads and caches the entire file content.

Free and total Space

Check the device storage capacity:

>>> fs.free()     # free space in kB
519680
>>> fs.size()     # total filesystem size in kB
522752

Async filesystem

For async workflows, use pypalmsens.DeviceFileSystemAsync with an pypalmsens.InstrumentManagerAsync:

>>> import asyncio
>>> import pypalmsens as ps

>>> async def main():
...     instruments = await ps.discover_async()
...     manager = ps.InstrumentManagerAsync(instruments[0])
...     await manager.connect()
...  
...     fs = ps.DeviceFileSystemAsync(manager)
...     paths = await fs.listdir()
...     for path in paths:
...         print(path)
...  
...     measurement = await fs.load_measurement(path)

>>> asyncio.run(main())
'Measurements/17-07-2026/LSV-10-00-25-0.dmeas'
'Measurements/17-07-2026/LSV-10-00-28-1.dmeas'
'Measurements/16-07-2026/CV-13-06-33-0.dmeas'
# ...

Error handling

Filesystem operations raise [pypalmsens._instruments.FileSystemException][] (a subclass of OSError) when a device operation fails:

>>> fs.read_text('nonexistent_file.txt')
FileSystemException: Error (!009F) while retrieving contents of '/nonexistent_file.txt'

Some common error codes:

!009D: Filesystem path was too long to handle
!009E: Filesystem the path was not valid
!009F: Filesystem could not find the file specified

Other error codes can be looked up in the MethodSCRIPT manual.