Can't build with CentOS 7

[DanielALS]

I'm trying to build your tools on CentOS 7. I started by installed the libmodbus in yum, but realized it was too old. I then cloned v1.4 from your repo and built that.

Cmake wasn't finding libmodbus.so at all, so I hacked the CMakeLists.txt by commenting out the find package part and just put in /usr/local/lib for the link_dirs. Cmake then appeared to run correctly.

Followed up with make and getting errors: >make Linking C executable mbpoll CMakeFiles/mbpoll.dir/src/mbpoll.c.o: In function vSigIntHandler: mbpoll.c:(.text+0x35): undefined reference to modbus_close mbpoll.c:(.text+0x41): undefined reference to modbus_free CMakeFiles/mbpoll.dir/src/mbpoll.c.o: In function vReportSlaveID: mbpoll.c:(.text+0x31e): undefined reference to modbus_set_slave mbpoll.c:(.text+0x363): undefined reference to modbus_report_slave_id mbpoll.c:(.text+0x45e): undefined reference to modbus_strerror CMakeFiles/mbpoll.dir/src/mbpoll.c.o: In function main: mbpoll.c:(.text.startup+0x5e0): undefined reference to modbus_new_tcp_pi mbpoll.c:(.text.startup+0x603): undefined reference to modbus_set_debug mbpoll.c:(.text.startup+0x63b): undefined reference to modbus_connect mbpoll.c:(.text.startup+0x697): undefined reference to modbus_set_response_timeout mbpoll.c:(.text.startup+0x750): undefined reference to modbus_read_registers mbpoll.c:(.text.startup+0x76f): undefined reference to modbus_strerror mbpoll.c:(.text.startup+0x7e6): undefined reference to modbus_set_slave mbpoll.c:(.text.startup+0x846): undefined reference to modbus_read_bits mbpoll.c:(.text.startup+0x899): undefined reference to modbus_read_input_bits mbpoll.c:(.text.startup+0x8b9): undefined reference to modbus_read_input_register' mbpoll.c:(.text.startup+0x8d6): undefined reference to modbus_set_slave mbpoll.c:(.text.startup+0x911): undefined reference to modbus_write_registers mbpoll.c:(.text.startup+0x930): undefined reference to modbus_strerror mbpoll.c:(.text.startup+0xa96): undefined reference to modbus_write_bits mbpoll.c:(.text.startup+0xaeb): undefined reference to modbus_new_rtu mbpoll.c:(.text.startup+0xb59): undefined reference to modbus_free mbpoll.c:(.text.startup+0xb65): undefined reference to modbus_strerror mbpoll.c:(.text.startup+0xc8c): undefined reference to modbus_write_bit mbpoll.c:(.text.startup+0xcad): undefined reference to modbus_write_register mbpoll.c:(.text.startup+0xdc7): undefined reference to modbus_rtu_set_serial_mode mbpoll.c:(.text.startup+0xdd9): undefined reference to modbus_rtu_set_rts collect2: error: ld returned 1 exit status make[2]: *** [mbpoll] Error 1 make[1]: *** [CMakeFiles/mbpoll.dir/all] Error 2 make: *** [all] Error 2

This seems like the modbus.h header is missing but it's in /usr/local/include/modbus.

Any help is appreciated, I think your tools will help me avoid Windows apps. TIA

[epsilonrt]

Hello, libmodbus is not installed correctly, you must follow the procedure: https://github.com/epsilonrt/mbpoll#installation. If you install libmodbus properly, you do not need to modify anything. Once installed libmodbus, delete everything in the cmake build directory. Do not forget the ldconfig!

[greearb]

I am trying to compile on Fedora-29. It too has a too-old libmodbus. I cloned latest libmodbus, built, and ran 'make install'. Files show up in /usr/local:

/usr/local/lib/libmodbus.la /usr/local/lib/libmodbus.so /usr/local/lib/libmodbus.so.5 /usr/local/lib/libmodbus.so.5.1.0 /usr/local/lib/pkgconfig/libmodbus.pc /usr/local/include/modbus/modbus.h

But, cmake cannot find it:

[greearb@ben-dt4 build]$ cmake ../ -- Checking for module 'libmodbus>=3.1.4' -- Package 'libmodbus', required by 'virtual:world', not found CMake Error at /usr/share/cmake/Modules/FindPkgConfig.cmake:457 (message): A required package was not found Call Stack (most recent call first): /usr/share/cmake/Modules/FindPkgConfig.cmake:642 (_pkg_check_modules_internal) CMakeLists.txt:42 (pkg_check_modules)

[greearb]

This makes it compile for me:

diff --git a/CMakeLists.txt b/CMakeLists.txt index 8e10f4a..6b69bc5 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -39,7 +39,11 @@ endif (NOT CL_USED) set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH})

find_package(PkgConfig REQUIRED) -pkg_check_modules (LIBMODBUS REQUIRED libmodbus>=3.1.4) +#pkg_check_modules (LIBMODBUS REQUIRED libmodbus>=3.1.4) + +set(LIBMODBUS_INCLUDE_DIRS /usr/local/include/modbus) +set(LIBMODBUS_LIBRARY_DIRS /usr/local/lib) +set(LIBMODBUS_LIBRARIES modbus)

link_directories(${LIBMODBUS_LIBRARY_DIRS}) add_definitions(${LIBMODBUS_CFLAGS})

[epsilonrt]

Hello, While your solution allows you to compile but the problem is not solved. You must have libmodbus version greater than or equal to 3.14. You tell me that you have compiled and installed libmodbus but what is its version? can you find it in the version.h file that is in libmodbus sources?

[greearb]

I don't see a version.h file, but here is the git commit ID:

ommit f1eb4bc7ccb09cd8d19ab641ee37637f8c34d16d (HEAD -> master, origin/master, origin/HEAD) Author: i-ky gl.ivanovsky@gmail.com Date: Tue Jul 10 15:58:45 2018 +0300

 Fixed MODBUS_GET_* macros in case of negative values

 In case resulting value should be negative it is incorrect to use '+' operator to construct it from pieces, because highest bytes will result in negative number after bitwise shift while others will stay positive. Replacing addition with '|' should solve the issue.

From repository:

url = https://github.com/stephane/libmodbus.git

Thanks, Ben

On 09/18/2019 12:07 AM, epsilonrt wrote:

Hello, While your solution allows you to compile but the problem is not solved. You must have libmodbus version greater than or equal to 3.14. You tell me that you have compiled and installed libmodbus but what is its version? can you find it in the version.h file that is in libmodbus sources?

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-- Ben Greear greearb@candelatech.com Candela Technologies Inc http://www.candelatech.com

[cristianlivella]

In case it will help anyone, I was having the same problem with Fedora 33, and I solved it by running this before sudo ldconfig.

echo "/usr/local/lib" | sudo tee -a /etc/ld.so.conf

[nightcatnl]

i downloaded libmodmus (3.1.10) from repo. Compiled it Installed it. test scripts (server and client) work fine.

Though I am not able to compile the mbpoll because of the above error

Why can cmake not find it ?

Really don't get it.