This is a professional quality product, with a free software download of the same standard. The comprehensive documentation makes it easy to interface both hardware and software. It is well worth the modest price, which includes shipping in the UK. I am using this device to control the intelligent charging of my Toshiba laptop battery in order to prolong battery life. Running Linux, I compiled the supplied 'controlio' source code without any problems to get the required 64 bit binary. A bash script runs as a cron job at five minute intervals, checking the charge level and switching the charging current on and off as required, via a relay controlled by three paralleled outputs of the GPIO interface. Many thanks for a great product, Peter.