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Problems with creating a library for PLCNext Engineer

fuadhfuadh
in PLCnext Engineer

Hello,

I am trying to creating a library for my project. The library is created with C++ and I am using the additional library pqxx for PostgreSQL communication with C++ inside my project. I followed the instructions how to build a C++ library in Eclipse. I am using Windows 11. And i get this kind of error:


[cmake]: PostgresDBLibrary.cpp:(.text._ZN10PostgresDB19PostgresDBComponentD2Ev[_ZN10PostgresDB19PostgresDBComponentD5Ev]+0x118): undefined reference to `pqxx::connection::close()'

[cmake]: c:/sdks/axcf2152/2024.0/sysroots/x86_64-w64-mingw32/usr/bin/arm-pxc-linux-gnueabi/../../libexec/arm-pxc-linux-gnueabi/gcc/arm-pxc-linux-gnueabi/11.4.0/ld.exe: CMakeFiles/PostgresDB.dir/intermediate/code/PostgresDBLibrary.cpp.o: in function `_GLOBAL__sub_I_PostgresDBLibrary.cpp':

[cmake]: PostgresDBLibrary.cpp:(.text.startup+0x5a): undefined reference to `pqxx::internal::demangle_type_name[abi:cxx11](char const*)'

[cmake]: c:/sdks/axcf2152/2024.0/sysroots/x86_64-w64-mingw32/usr/bin/arm-pxc-linux-gnueabi/../../libexec/arm-pxc-linux-gnueabi/gcc/arm-pxc-linux-gnueabi/11.4.0/ld.exe: PostgresDBLibrary.cpp:(.text.startup+0x74): undefined reference to `pqxx::internal::demangle_type_name[abi:cxx11](char const*)'

[cmake]: c:/sdks/axcf2152/2024.0/sysroots/x86_64-w64-mingw32/usr/bin/arm-pxc-linux-gnueabi/../../libexec/arm-pxc-linux-gnueabi/gcc/arm-pxc-linux-gnueabi/11.4.0/ld.exe: PostgresDBLibrary.cpp:(.text.startup+0xa0): undefined reference to `pqxx::internal::demangle_type_name[abi:cxx11](char const*)'

[cmake]: c:/sdks/axcf2152/2024.0/sysroots/x86_64-w64-mingw32/usr/bin/arm-pxc-linux-gnueabi/../../libexec/arm-pxc-linux-gnueabi/gcc/arm-pxc-linux-gnueabi/11.4.0/ld.exe: PostgresDBLibrary.cpp:(.text.startup+0xb4): undefined reference to `pqxx::internal::demangle_type_name[abi:cxx11](char const*)'

[cmake]: collect2.exe: error: ld returned 1 exit status

[cmake]: make[2]: *** [CMakeFiles/PostgresDB.dir/build.make:174: libPostgresDB.so] Error 1

[cmake]: make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/PostgresDB.dir/all] Error 2

[cmake]: make: *** [Makefile:136: all] Error 2

Comments

  • Eduard PLCnext TeamEduard PLCnext Team

    Hello fuadh,

    it seems that the compilation of the project "PostgreSQL" with PLCnext SDK fails. I'm not familiar with "PostgreSQL" C++ project but maybe there are members here who can help you. Please note the PLCnext FW provides the SQLite-DB by default, you can simply configure it in PLCnext Engineer Project. Please find the introduction in PLCnext Info Center: DataLogger concept (plcnext.help)

    I hope it helps you.

    BR Eduard

  • fuadhfuadh

    i want to communicate the plc device with my database i created on my local machine, thats why im using postgresql. The problem happened when i need to import a library in my code. Is there any way how to solve this problem?

  • Eduard PLCnext TeamEduard PLCnext Team

    Hello fuadh,

    to solve the problems, you need SW-Developer knowledge, you can try to contact the development of PostgreSQL and ask for Support/Compilation: PostgreSQL: Support

    BR Eduard

  • fuadhfuadh

    Is there any good tutorial how to create a simple library for PLCnext using additional c++ libraries ?

  • Eduard PLCnext TeamEduard PLCnext Team
    edited June 2024

    Hello fuadh,

    please find the example under following Link:

    CppExamples/Examples/IncludeOpenSourceLibrary/README.md at master · PLCnext/CppExamples · GitHub

    BR Eduard

  • fuadhfuadh

    I tried this example you sent me, but it has errors: error C2370: 'ne10_float32_t': redefinition; different storage class and similar errors. I didnt change anything from the library Ne10 and i followed the instructions for Eclipse. Is there anybody who can help with this ?

  • Martin [PLCnext Technology Team]Martin [PLCnext Technology Team]

    I cross-compiled the Ne10 library on a Debian machine using the SDK for AXCF2152 FW 2024.0, and the instructions in the building.md file. Here are the basic commands that build a static Ne10 library for that platform:

    git clone https://github.com/projectNe10/Ne10.git
cd Ne10
mkdir build && cd build
source /opt/pxc/sdk/AXCF2152/2024.0/environment-setup-*  # your path will be different
export NE10_LINUX_TARGET_ARCH=armv7
cmake -DGNULINUX_PLATFORM=ON ..
make

    You should be able to build a shared library (and not the static library) using the NE10_BUILD_STATIC and NE10_BUILD_SHARED cmake flags.

  • fuadhfuadh

    I want to cross compile the libpqxx library, but i get this error :

    libpqxx-7.9.a(connection.obj) : error LNK2019: unresolved external symbol __imp_ioctlsocket referenced in function "pub

    lic: void __cdecl pqxx::connection::set_blocking(bool)& " (?set_blocking@connection@pqxx@@QEGAAX_N@Z) [C:\Libraries\lib

    pqxx\build\test\runner.vcxproj]

    libpqxx-7.9.a(connection.obj) : error LNK2019: unresolved external symbol __imp_WSAGetLastError referenced in function

    "public: void __cdecl pqxx::connection::set_blocking(bool)& " (?set_blocking@connection@pqxx@@QEGAAX_N@Z) [C:\Libraries

    \libpqxx\build\test\runner.vcxproj]

    libpqxx-7.9.a(wait.obj) : error LNK2001: unresolved external symbol __imp_WSAGetLastError [C:\Libraries\libpqxx\build\t

    est\runner.vcxproj]

    libpqxx-7.9.a(wait.obj) : error LNK2019: unresolved external symbol __imp_WSAPoll referenced in function "void __cdecl

    pqxx::internal::wait_fd(int,bool,bool,unsigned int,unsigned int)" (?wait_fd@internal@pqxx@@YAXH_N0II@Z) [C:\Libraries\l

    ibpqxx\build\test\runner.vcxproj]

    C:\Libraries\libpqxx\build\test\Release\runner. : fatal error LNK1120: 3 unresolved externals [C:\Libraries\libpqxx\bui

    ld\test\runner.vcxproj]


    interesting when i use this command for normal compiling :  g++ -o main main.cpp -I"C:\Libraries\libpqxx\include" -I"C:\Program Files\PostgreSQL\16\include" -L"C:\Libraries\libpqxx\lib" -L"C:\Program Files\PostgreSQL\16\lib" -lpqxx -lpq -lws2_32 -std=c++17, it works, but when i use this toolchain i get the error above ?

  • Martin [PLCnext Technology Team]Martin [PLCnext Technology Team]
    edited July 2024

    It seems like one if the issues with the libpqxx cross-compilation process will be this:

    image.png
    image.png


    These prerequisites would be required for the target platform (i.e. the PLCnext Control device) rather than for the host platform. That would explain why you can build it without cross-compiling - you've probably fulfilled this prerequisite on the host, and in that case you're not cross-compiling for another platform.

    I don't have any ideas on how to make either the libpq library or the full ProgresSQL development package available during the cross-compilation process. You might be able to cross-compile libpq from source, and somehow link to that library during cross-compilation. That is a general cross-compilation issue, not related to PLCnext Technology, so perhaps someone on a ProgresSQL forum can help with that.

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