The six-stage controller was developed for the control of compressor groups of up to 6 machines, and/or the control of compressors with bypass-valves (max. 3 machines). The basic gas characteristics are part of the fixed program data - therefore, it is possible to execute a pressure control (4...20 mA) and to show the temperature values at the same time. The compressor running times can be optimised by help of the sequential or time-conditioned load replacement. The controller that can be parametered in various ways has an alarm contact and a hour meter. Networking of the controller takes place via the ST-Bus interface.