Shopbus Modules are specifically designed for two reasons; firstly, creating large systems where more interfaces are needed than one XM controller with connected EM modules can provide. And secondly; allowing large interspacing between several control units, when Elements are needed far apart from each other. The Shopbus architecture enables connecting multiple XM-like controller units together, with the possibility of using long cable lengths between the units. All the while, the interfacing towards the connected device can still take place through one serial communication connection.