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<== Date ==>		<== Thread ==>

Subject:	Can't import PyEpics on CentOS 7
From:	Chiang, Liang-Chih [江良志] via Tech-talk <[email protected]>
To:	"[email protected]" <[email protected]>
Date:	Thu, 9 Jan 2020 03:29:31 +0000

Hi,

I could install PyEpics on CentOS 6.10(x86_64) and Python 3.7,

and there is no problem using caget, caput, PV, Motor, etc.. of PyEpics.

However, in the following environment, 'import epics' will result in error.

CentOS version 7.4, x86_64 architecture

Linux kernel version 3.10.0

Python 3.7 (created by Miniconda virtual environment)

The PyEpics was installed by the following command:

$ conda install -c GSECARS pyepics

In Python interactive shell:

>>> import epics

Traceback (most recent call last):

File "/home/user/miniconda3/envs/py37/lib/python3.7/ctypes/__init__.py", line 97, in CFUNCTYPE

return _c_functype_cache[(restype, argtypes, flags)]

KeyError: (None, (<class 'epics.dbr.access_rights_handler_args'>,), 1)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

File "/home/user/miniconda3/envs/py37/lib/python3.7/site-packages/epics/__init__.py", line 29, in <module>

from . import ca

File "/home/user/miniconda3/envs/py37/lib/python3.7/site-packages/epics/ca.py", line 761, in <module>

dbr.access_rights_handler_args)

File "/home/user/miniconda3/envs/py37/lib/python3.7/site-packages/epics/dbr.py", line 339, in make_callback

return ctypes.CFUNCTYPE(None, args)(func)

File "/home/user/miniconda3/envs/py37/lib/python3.7/ctypes/__init__.py", line 99, in CFUNCTYPE

class CFunctionType(_CFuncPtr):

TypeError: item 1 in _argtypes_ passes a struct/union with a bitfield by value, which is unsupported.

I also tried installing PyEpics by 'pip install pyepics', similar error message will show up when installing.

Best regards.

LiangChih Chiang

Beamline Group

National Synchrotron Radiation Research Center (NSRRC)

Replies:: Re: Can't import PyEpics on CentOS 7 Matt Newville via Tech-talk

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ANJ, 08 Jan 2020