In the center of the picture you see the main controller (some empty panels are not installed here - they are now to comply with the EMC laws). The modules are (from left to right): The processor resposible for the communication with the workstation. It collects the meteorologic data, too. The controller for all the tasks related to moving the carriage and reading the laser interferometer. It is stuffed with connectors. Next there is the IEC-bus interface. The black cable connects the controller to the laser transducer (partly visible at the top of the picture). The next module (after the gap) is a multiplexer for the temperature subsystem. It selects the sensor to read under control of the leftmost processor. The last module is the power supply for the box. It includes a security loop to protect the operator from hazards.