Epics Channel Access for Python

PyEpics is an interface for the Channel Access (CA) library of the Epics Control System to the Python Programming language. The pyepics package provides an epics module to python, with methods for reading from and writing to Epics Process Variables (PVs) via the CA protocol. The package includes a thin and fairly complete layer over the lowest-level Channel Access library in the ca module, and higher level abstractions built on top of this basic functionality.

The package includes a simple interface to CA similar to the Unix command-line tools with functions epics.caget(), epics.caput(), epics.cainfo(), and epics.camonitor(). For an object-oriented interface, there is a pv.PV class which represents an Epics Process Variable as a full-featured and convenient Python object. Additional modules provide higher-level programming support to CA, including grouping related PVs into a device.Device (with a number of predefined devices ready to use), for creating alarms in alarm.Alarm, and for saving PVs values in the autosave module. There is also support for conveniently using epics PVs to wxPython widgets in the wx module, and some support for using PyQt widgets in the qt module.

Some applications built with pyepics that are available at https://github.com/pyepics/epicsapps/.

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• Downloading and Installation
  • Installation
  • Prerequisites and Dependencies, Supported Systems
  • Getting Started, Setting up the Epics Environment
  • Testing
  • Development Version
  • Getting Help
  • License
  • Acknowledgments
• PyEpics Overview
  • Quick Start
  • Simple epics functions: caget(), caput(), etc.
  • Motivation and design concepts
  • Status
• PV: Epics Process Variables
  • The PV class
  • String representation for a PV
  • Automatic Monitoring of a PV
  • User-supplied Callback functions
  • User-supplied Connection Callback functions
  • User-supplied Access Rights Callback functions
  • Put with wait, put callbacks, and put_complete
  • The get_pv() function and _PVcache_ cache of PVs
  • Examples
• ca: Low-level Channel Access module
  • General description, difference with C library
  • Initialization, Finalization, and Life-cycle
  • Using the CA module
  • Implementation details
  • User-supplied Callback functions
  • Omissions
  • CAThread class
  • Examples
• Working with waveform / array data
  • Arrays without Numpy
  • Variable Length Arrays: NORD and NELM
  • Character Arrays
  • Example handling Large Arrays
• Devices: collections of PVs
  • Overview
  • Epics Motor Device
  • Other Device Examples
• Alarms: respond when a PV goes out of range
  • Overview
  • Alarm Example
• Auto-saving: simple save/restore of PVs
  • save_pvs()
  • restore_pvs()
  • AutoSaver class
  • Supported Data Types
• wx: wxPython Widgets for Epics
  • PV-aware Widgets
  • Decorators and other Utility Functions
  • wxMotorPanel Widget
  • OGL Classes
• Advanced Topic with Python Channel Access
  • The wait and timeout options for get(), ca.get_complete()
  • Strategies for connecting to a large number of PVs
  • time.sleep() or epics.poll()?
  • Using Python Threads
  • Using Multiprocessing with PyEpics