PyEpics: Epics Channel Access for Python
PyEpics is a Python interface to the EPICS Channel Access (CA) library for the EPICS control system.
The PyEpics module includes both low-level (C-like) and higher-level access (with Python objects) to the EPICS Channnel Access (CA) protocol. Python’s ctypes library is used to wrap the basic CA functionality, with higher level objects on top of that basic interface. This approach has several advantages including no need for extension code written in C, better thread-safety, and easier installation on multiple platforms.
Installation
This package is supported and tested with Python 3.8 through 3.12. Shared libraries needed for Epics Channel Access are provided for Windows, MacOS, and Linux, and used by default. If you wish to use your own versions of the CA shared libraries, that can be controlled with an environmental variable.
To install the package, use:
pip install pyepics
To install from source, download the source kit for the latest release from PyPI (https://pypi.org/project/pyepics/) or Github (https://github.com/pyepics/pyepics/releases), unpack that and use:
pip install .
For additional installation details, see the INSTALL file. Binary installers for Windows are available.
License
This code is distributed under the Epics Open License
Overview
Pyepics provides two principle modules: ca, and pv, and functions caget(), caput(), and cainfo() for the simplest of interaction with EPICS. In addition, there are modules for Epics Motors and Alarms, autosave support via CA, and special widget classes for using EPICS PVs with wxPython.
caget(), caput() and cainfo()
The simplest interface to EPICS Channel Access provides functions caget(), caput(), and cainfo(), similar to the EZCA interface and to the EPICS-supplied command line utilities. These all take the name of an Epics Process Variable as the first argument:
~> python
>>> from epics import caget, caput, cainfo
>>> print(caget('XXX:m1.VAL'))
1.200
>>> caput('XXX:m1.VAL',2.30)
1
>>> cainfo('XXX.m1.VAL')
== XXX:m1.VAL (double) ==
value = 2.3
char_value = 2.3000
count = 1
units = mm
precision = 4
host = xxx.aps.anl.gov:5064
access = read/write
status = 1
severity = 0
timestamp = 1265996455.417 (2010-Feb-12 11:40:55.417)
upper_ctrl_limit = 200.0
lower_ctrl_limit = -200.0
upper_disp_limit = 200.0
lower_disp_limit = -200.0
upper_alarm_limit = 0.0
lower_alarm_limit = 0.0
upper_warning_limit = 0.0
lower_warning = 0.0
PV is monitored internally
no user callbacks defined.
=============================
PV: Object Oriented CA interface
The general concept is that an Epics Process Variable is implemented as a Python PV object, which provides a natural way to interact with EPICS.
>>> import epics
>>> pv = epics.PV('PVName')
>>> pv.connected
True
>>> pv.get()
3.14
>>> pv.put(2.71)
Channel Access features that are included here:
user callbacks - user-supplied Python function(s) that are run when a PV’s value, access rights, or connection status changes
control values - a full Control DBR record can be requested
enumeration strings - enum PV types have integer or string representation, and you get access to both
put with wait - The PV.put() method can optionally wait until the record is done processing (with timeout)
Features that you won’t have to worry about:
connection management (unless you choose to worry about this)
PV record types - this is handled automatically.
1 maintainer
Release files for pyepics 3.5.10
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Source distribution (sdist)
| File | Size | Uploaded | |
|---|---|---|---|
| pyepics-3.5.10.tar.gz | 6.2 MB | Details |
Built distribution (wheel)
| File | Interpreter | ABI | Platform | Reset |
|---|---|---|---|---|
| pyepics-3.5.10-py3-none-any.whl | Python 3 | none | any | Details |
Total release size: 11.5 MB
Release files / pyepics-3.5.10.tar.gz
| Download URL | pyepics-3.5.10.tar.gz |
|---|---|
| Size | 6.2 MB |
| Tags | Source |
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| Size | 5.3 MB |
| Tags | Python 3 |
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