Typhos
EPICS is a flexible and powerful controls system to access to experimental information, however, the relation and meaning of process variables is often obscure. Many of the user interfaces for EPICS information reflect this, as walls of buttons and flashing lights bombard the user with little thought to structure or cohesion.
Typhos addresses this by providing an automated way to generate screens based on a provided hierarchy of devices and signals. Built using PyDM, a PyQt based display manager developed at SLAC National Laboratory, Typhos utilizes a large toolkit of widgets to display EPICS information. For each process variable, a corresponding widget is created based on; the importance to the average operator, the type of value the EPICS PV will return, and whether a user should be allowed to write to the variable. These widgets are then placed in a convenient tab-based system to only show the necessary information for basic function, but still allow access to more advanced signals.
Instead of reinventing a new way to specify device structures, Typhos uses Ophyd, a library to abstract EPICS information into consistently structured Python objects. Originally built for scripting experimental procedures at NSLS-II, Ophyd represents devices as combinations of components which are either signals or nested devices. Then, either at runtime or by using the defaults of the representative Python class, these signals are sorted into different categories based on their relevance to operators. Typhos uses this information to craft user interfaces.