This is Nagios plugin for Modbus TCP and RTU. The first version of this plugin was taken from http://exchange.nagios.org/directory/Plugins/Network-and-Systems-Management/Check_modbus_tcp/details Added many useful features: - support of IPv6 / IPv4 - support of DNS names - serial port connections (RS232 and RS485) with Modbus RTU (when compiled with libmodbus >= 3.0.0) - support of many data formats (unsigned/signed int16_t, int32_t, float, double) - support of several data orders (LSB, MSB and some others) - retries can be sent to get reliable answer - supports performance data - supports creation dump of the registers in different formats (binary, hexadecimal, decimal) - support binary dump as an input source for data (useful for off-line data) - separate lock files for input and output In general, plugin can be build as usual ./autogen.sh ./configure make make install When you are trying to build plugin under MinGW, then maybe you will need to define path for libmodbus explicitly. libmodbus is installed by default in /usr/local/lib. In MinGW you will need to run ./configure LDFLAGS=-L/usr/local/lib CPPFLAGS=-I/usr/local/include instead of just ./configure For usage details see manual page or run ./check_modbus --help.