I am not able to install pylibmodbus library as cffi is not installed.
If I try to install cffi I get the following issue
pi@raspberrypi:~ $ pip3 install cffi Collecting cffi Using cached https://files.pythonhosted.org/packages/93/1a/ab8c62b5838722f29f3daffcc8d4bd61844aa9b5f437341cc890ceee483b/cffi-1.12.3.tar.gz Collecting pycparser (from cffi) Using cached https://www.piwheels.org/simple/pycparser/pycparser-2.19-py2.py3-none-any.whl Building wheels for collected packages: cffi Running setup.py bdist_wheel for cffi ... error Complete output from command /usr/bin/python3 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-pqz_612d/cffi/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" bdist_wheel -d /tmp/tmpzpgl54b1pip-wheel- --python-tag cp35: Package libffi was not found in the pkg-config search path. Perhaps you should add the directory containing `libffi.pc' to the PKG_CONFIG_PATH environment variable No package 'libffi' found Package libffi was not found in the pkg-config search path. Perhaps you should add the directory containing `libffi.pc' to the PKG_CONFIG_PATH environment variable No package 'libffi' found Package libffi was not found in the pkg-config search path. Perhaps you should add the directory containing `libffi.pc' to the PKG_CONFIG_PATH environment variable No package 'libffi' found Package libffi was not found in the pkg-config search path. Perhaps you should add the directory containing `libffi.pc' to the PKG_CONFIG_PATH environment variable No package 'libffi' found Package libffi was not found in the pkg-config search path. Perhaps you should add the directory containing `libffi.pc' to the PKG_CONFIG_PATH environment variable No package 'libffi' found running bdist_wheel running build running build_py creating build creating build/lib.linux-armv7l-3.5 creating build/lib.linux-armv7l-3.5/cffi copying cffi/vengine_cpy.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/model.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/vengine_gen.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/error.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/backend_ctypes.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/verifier.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/lock.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/api.py
-> build/lib.linux-armv7l-3.5/cffi copying cffi/setuptools_ext.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/__init__.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/cffi_opcode.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/ffiplatform.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/recompiler.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/cparser.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/pkgconfig.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/commontypes.py -> build/lib.linux-armv7l-3.5/cffi copying cffi/_cffi_include.h -> build/lib.linux-armv7l-3.5/cffi copying cffi/parse_c_type.h -> build/lib.linux-armv7l-3.5/cffi copying cffi/_embedding.h -> build/lib.linux-armv7l-3.5/cffi copying cffi/_cffi_errors.h -> build/lib.linux-armv7l-3.5/cffi running build_ext building '_cffi_backend' extension creating build/temp.linux-armv7l-3.5 creating build/temp.linux-armv7l-3.5/c arm-linux-gnueabihf-gcc
-pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -g -fdebug-prefix-map=/build/python3.5-RUbMX3/python3.5-3.5.3=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -DUSE__THREAD -DHAVE_SYNC_SYNCHRONIZE -I/usr/include/ffi -I/usr/include/libffi -I/usr/include/python3.5m -c c/_cffi_backend.c -o build/temp.linux-armv7l-3.5/c/_cffi_backend.o c/_cffi_backend.c:15:17: fatal error: ffi.h: No such file or directory
#include <ffi.h>
^ compilation terminated. error: command 'arm-linux-gnueabihf-gcc' failed with exit status 1
---------------------------------------- Failed building wheel for cffi Running setup.py clean for cffi Failed to build cffi Installing collected packages: pycparser, cffi Running setup.py install for cffi ... error
Complete output from command /usr/bin/python3 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-pqz_612d/cffi/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install
--record /tmp/pip-m_en9z1k-record/install-record.txt --single-version-externally-managed --compile --user --prefix=:
Package libffi was not found in the pkg-config search path.
Perhaps you should add the directory containing `libffi.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libffi' found
Package libffi was not found in the pkg-config search path.
Perhaps you should add the directory containing `libffi.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libffi' found
Package libffi was not found in the pkg-config search path.
Perhaps you should add the directory containing `libffi.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libffi' found
Package libffi was not found in the pkg-config search path.
Perhaps you should add the directory containing `libffi.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libffi' found
Package libffi was not found in the pkg-config search path.
Perhaps you should add the directory containing `libffi.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libffi' found
running install
running build
running build_py
creating build
creating build/lib.linux-armv7l-3.5
creating build/lib.linux-armv7l-3.5/cffi
copying cffi/vengine_cpy.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/model.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/vengine_gen.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/error.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/backend_ctypes.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/verifier.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/lock.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/api.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/setuptools_ext.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/__init__.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/cffi_opcode.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/ffiplatform.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/recompiler.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/cparser.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/pkgconfig.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/commontypes.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/_cffi_include.h -> build/lib.linux-armv7l-3.5/cffi
copying cffi/parse_c_type.h -> build/lib.linux-armv7l-3.5/cffi
copying cffi/_embedding.h -> build/lib.linux-armv7l-3.5/cffi
copying cffi/_cffi_errors.h -> build/lib.linux-armv7l-3.5/cffi
running build_ext
building '_cffi_backend' extension
creating build/temp.linux-armv7l-3.5
creating build/temp.linux-armv7l-3.5/c
arm-linux-gnueabihf-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -g -fdebug-prefix-map=/build/python3.5-RUbMX3/python3.5-3.5.3=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -DUSE__THREAD -DHAVE_SYNC_SYNCHRONIZE -I/usr/include/ffi -I/usr/include/libffi -I/usr/include/python3.5m -c c/_cffi_backend.c -o build/temp.linux-armv7l-3.5/c/_cffi_backend.o
c/_cffi_backend.c:15:17: fatal error: ffi.h: No such file or directory
#include <ffi.h>
^
compilation terminated.
error: command 'arm-linux-gnueabihf-gcc' failed with exit status 1
---------------------------------------- Command "/usr/bin/python3 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-pqz_612d/cffi/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install
--record /tmp/pip-m_en9z1k-record/install-record.txt --single-version-externally-managed --compile --user --prefix=" failed with error code 1 in /tmp/pip-build-pqz_612d/cffi/
