# Standard Methods

The common device API shared by every Plesty device (connection, I/O and lifecycle). See [Usage](usage.md) for how to use them.

```{eval-rst}
.. py:function:: connect() -> bool
   :no-index:

   :bdg-secondary-line:`standard`

   Open the VISA connection to the PM100D.

   :returns: ``True`` if the connection is successfully open, ``False`` otherwise.
```

```{eval-rst}
.. py:function:: disconnect() -> NoneType
   :no-index:

   :bdg-secondary-line:`standard`

   Close the VISA connection and release all resources.

```

```{eval-rst}
.. py:function:: identity() -> str
   :no-index:

   :bdg-secondary-line:`standard`

   Return the instrument identification string (``\*IDN?``).

   :returns: Identification string in the form ``'THORLABS,PM100D,<serial>,<firmware>'``.
```

```{eval-rst}
.. py:function:: check_errors() -> list
   :no-index:

   :bdg-secondary-line:`standard`

   Query the error queue and return any active error messages.

   :returns: Empty list when the device reports no error (``0,"No error"``); a one-element list containing the raw error string otherwise.
```

```{eval-rst}
.. py:function:: check_operatability() -> bool
   :no-index:

   :bdg-secondary-line:`standard`

   Return ``True`` if the VISA session is open.

   :returns: ``True`` when the traffic manager exists and its session is open.
```

```{eval-rst}
.. py:function:: write(key: str, value: str | float | int | bool) -> bool
   :no-index:

   :bdg-secondary-line:`standard`

   Write a configuration parameter value to the device after validation.

   :param key: Name of the parameter to write (as listed on the Parameters page).
   :type key: str
   :param value: New value; validated against the parameter's type and range before being sent to the device.
   :type value: str | float | int | bool
   :returns: ``True`` if the write succeeded, ``False`` otherwise (e.g. a permission check failed).
```

```{eval-rst}
.. py:function:: query(key: str) -> Any
   :no-index:

   :bdg-secondary-line:`standard`

   Query a configuration parameter value from the device.

   :param key: Name of the parameter to read (as listed on the Parameters page).
   :type key: str
   :returns: The parameter's current value, converted to its declared type.
```

```{eval-rst}
.. py:function:: reset() -> NoneType
   :no-index:

   :bdg-secondary-line:`standard`

   Send ``\*RST`` to return the instrument to its factory default state.

```

```{eval-rst}
.. py:function:: clear() -> NoneType
   :no-index:

   :bdg-secondary-line:`standard`

   Send ``\*CLS`` to clear the status registers and error queue.

```

```{eval-rst}
.. py:function:: status() -> DeviceStatus
   :no-index:

   :bdg-secondary-line:`standard`

   Return a point-in-time snapshot of the device's operational state.

   :returns: The current :class:`DeviceStatus`.
```

```{eval-rst}
.. py:function:: set_data_path(path: str | os.PathLike[str]) -> str
   :no-index:

   :bdg-secondary-line:`standard`

   Set the directory where this device stores acquired data.

   :param path: Target directory, absolute or relative to the device's default data path.
   :type path: str | os.PathLike[str]
   :returns: The directory now in effect, in the configured spelling of its data root — a mapped drive stays a mapped drive; resolution is used for the containment checks only.
```

```{eval-rst}
.. py:function:: get_data_path() -> str
   :no-index:

   :bdg-secondary-line:`standard`

   Return the directory currently used for acquired data.

   :returns: The directory in effect, in its configured spelling: the last one set by a client, or the device's configured default. The directory is created if missing — the configured default is otherwise never created anywhere (construction is side-effect-free), and vendor software validating the directory rejects one that does not exist (plesty-lib#31).
```