Abstract: The invention relates to a device for an inherently safe signal matching of signals being exchanged between an automating system (2) and field devices (3). The device (1) contains input/output modules (4), which can be plugged into a backwall plate (19) and which combine the functions of conventional input/output modules and modules for voltage separation. The backwall plate (19) supports data lines (20) of a local bus (8), as well a current supply lines (21). A communications module (9) is connected on the one hand with the local bus (8), and on the other hand with a field bus (12). The communications module (9) contains device, for memorizing (22) and processing (16) data, and makes possible an asynchronous data exchange between an automating system (2) and the input/output modules (4).