Often in my day I find myself testing and debugging devices that communicate via the modbus protocol. In an effort to save myself time, I have tried several downloadable applications but always came to the same conclusion - Why pay money for something when it s not that hard to build myself? Also, given that modbus is a 30 year old standard, it makes it difficult to find current code that is usable in today s popular languages. What follows is a brief descr iption of the madness behind the modbus and a small application that I find myself using daily when testing RS232 modbus devices. The code is hardly robust, but it gets the job done in the sense that it works and it is easy to use and alter - two features I find the most important in a lab setting. I hope you find this of some use!-Often in my day I find myself testing and debugging devices that communicate via the modbus protocol. In an effort to save myself time, I have tried several downloadable applications but always came to the same conclusion -　Why pay money for something when it s not that hard to build myself?　Also, given that modbus is a 30 year old standard, it makes it difficult to find current code that is usable in today s popular languages. What follows is a brief descr iption of the madness behind the modbus and a small application that I find myself using daily when testing RS232 modbus devices. The code is hardly robust, but it gets the job done in the sense that it works and it is easy to use and alter - two features I find the most important in a lab setting. I hope you find this of some use!