Architecture
============

The layers of a typical application are:

.. graphviz::

   digraph architecture {
       rankdir=TB;
       node [shape=box];
       "Script or GUI" -> "Measure subclass";
       "Measure subclass" -> "MGraph";
       "MGraph" -> "Device drivers";
       "Device drivers" -> "Communication classes";
       "Measure subclass" -> "Autosave and history";
       "Measure subclass" -> "EUT monitor";
       "Measure subclass" -> "Report";
       "SCUQ" -> "Measure subclass" [style=dashed];
       "SCUQ" -> "MGraph" [style=dashed];
       "SCUQ" -> "Device drivers" [style=dashed];
   }

Script or GUI
-------------

The operator layer loads configuration, creates or restores the measurement
class, and starts measurement and evaluation. Qt applications move long
hardware operations into worker threads.

``Measure`` and measurement classes
-----------------------------------

``Measure`` provides shared infrastructure for logging, user interaction,
autosave, pickle history, device initialization, and safe shutdown. ``MSC``,
``TEMCell``, and ``AmplifierTest`` add their domain workflows.

``MGraph``
----------

``MGraph`` reads DOT topology, evaluates conditions with an explicit context,
creates device instances, and calculates path corrections. Leveling and
amplifier protection also use the measurement graph.

Device drivers and communication
--------------------------------

Base drivers define the common API for a device class. Instrument-specific
drivers map that API to SCPI or proprietary commands. Communication classes
encapsulate GPIB, serial, Prologix, and other transports.

SCUQ
----

SCUQ carries nominal value, unit, uncertainty, and correlation through the
calculation. mpylab's centralized helpers convert between linear and
logarithmic representations.