Visual LTL (VLTL) is a graphical development environment to easily and comfortably configure the data loggers. This environment contains a set of graphical objects which are connected by lines, to show their relation to each other, and are used for developing and creating new objects. Standard objects as well as new ones can be saved in libraries and protected by passwords. This environment additionally offers effortless reusability of already created objects and libraries in new configurations. One click is all that is needed to compile the configuration to the G.i.N. data logger programming language LTL and transfer it to the data logger.