Since the version v3.0, liblightmodbus is a header-only library. This decision was made due to large number of questions and problems regarding compilation on different platforms. As it turns out, CMake doesn't go very well with embedded projects.

In order to integrate liblightmodbus with your project you need to add liblightmodbus/include to you include paths. If you're using CMake you might do that automatically by including lightmodbus package.

In your source code you should be using #include <lightmodbus/lightmodbus.h> to include the library (or lightmodbus.hpp if you wish to try the experimental C++ API). The library can be configured by defining certain macros before including that file:

Macro	Description
`LIGHTMODBUS_IMPL`	Include implementation
`LIGHTMODBUS_SLAVE`	Includes slave part of the library
`LIGHTMODBUS_FxxS`	Adds function `xx` to modbusSlaveDefaultFunctions
`LIGHTMODBUS_SLAVE_FULL`	Includes slave part of the library and adds all functions to modbusSlaveDefaultFunctions
`LIGHTMODBUS_MASTER`	Includes master part of the library
`LIGHTMODBUS_FxxM`	Adds function `xx` to modbusMasterDefaultFunctions
`LIGHTMODBUS_MASTER_FULL`	Includes master part of the library and adds all functions to modbusMasterDefaultFunctions
`LIGHTMODBUS_FULL`	Equivalent of both `LIGHTMODBUS_SLAVE_FULL` and `LIGHTMODBUS_MASTER_FULL`
`LIGHTMODBUS_DEBUG`	Includes some debugging utilities
`LIGHTMODBUS_MASTER_OMIT_REQUEST_CRC`	Omits request CRC calculation for request on master side
`LIGHTMODBUS_WARN_UNUSED`	Compiler attribute to warn about unused return value. `__attribute__((warn_unused_result))` by default
`LIGHTMODBUS_ALWAYS_INLINE`	Compiler attribute to always inline a function. `__attribute__((always_inline))` by default

Each time lightmodbus.h is included, the set of defined configuration macros must be the same (except from LIGHTMODBUS_IMPL which should only be used once).

Moreover, it's very important that you include implementation of the library functions (LIGHTMODBUS_IMPL) in exactly one place in your codebase. It may be a good idea to create a source file dedicated specifically for including implementation of liblightmodbus. For instance, you may want to create lightmodbus-impl.c containing:

#include "my-consistent-liblightmodbus-config-macros.h"
#define LIGHTMODBUS_IMPL
#include <lightmodbus/lightmodbus.h>

See example integration of liblightmodbus with a simple demo project here.

Embedded platforms

Since v3.0 building liblightmodbus on embedded platforms is no different from building it for your PC. You're only required to add the header files to your project.

Note: Tip: Be sure to enable linking time optimizations (-flto) when building your project to further reduce the size of your binary. If your compiler doesn't support it, you can try -ffunction-sections -fdata-sections -Wl,--gc-sections to delete unused functions.

ESP-IDF

Liblightmodbus can be used as an ESP-IDF component. The relevant configuration is kept on esp-idf branch and in liblightmodbus-esp repository. It can be cloned directly to your components directory with:

git clone https://github.com/Jacajack/liblightmodbus-esp.git

When using liblightmodbus with ESP-IDF, the implementation of the library functions is automatically included for you - you shouldn't use LIGHTMODBUS_IMPL anywhere in your code. You shouldn't define any config options when including lightmodbus.h either. Library configuration is read from esp.config.h and sdkconfig.h and should be edited with idf.py menuconfig.