I have working device, that operates with RAM (random access memory). I want to grab RAM dump. I think it must be a hardware option. Is there a way to do this? Maybe anybody have some expirience?
You'll need to get access to the OS to run your code to dump the RAM (could be as simple as
dd if=/dev/mem of=/tmp/ramdump). There may be hardware workarounds to get the data directly from the RAM chips or logic traces but they likely involve multi-K$ professional logic analyzers or testing tools. In any case, you gave us too little information for a really useful answer.