FreeMODBUS - A Modbus ASCII/RTU and TCP implementation

latest release v1.5 - 6 June 2010


You can get the current version of FreeModbus at This versions includes a lot of functions like Modbus RTU/ASCII, Modbus TCP, input/holding register access, discrete registers and more. In addition it has been ported to the following platforms: FreeRTOS/Cortex M3 SAM3S, FreeRTOS/ARM STR71X, FreeRTOS/ARM AT91SAM7X, lwIP/PPP/STR71X, Freescale MCF5235, lwIP/MCF5235, Atmel AVR ATMega168, TI-MSP430, Win32 and Linux.


Donations are appreciated and gratefully received! I am looking for HCS12 and Renesas development platforms for porting purposes. If available the kit should include a programmer/debugger interface as well as a target system. In addition money is also accepted and will be used for supporting FreeModbus development. Note that donations are not required in order to use or download FreeModbus. They are completely voluntarily
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If you want to take a look at the source you can find information on how to access the CVS repository at FreeModbus CVS repository. In case you only want to take a look at the code WebCVS access is also available.


FreeMODBUS is provided by Embedded Solutions. Embedded Solutions provides commercial support for FreeMODBUS at a hourly basis. In addition we have created to commercial versions of our popular MODBUS stack which includes a master and a slave stack.

FreeMODBUS library and web page maintained by Christian Walter [wolti at sil dot at]
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FreeMODBUS is sponsored and provided by embedded solutions embedded solutions
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