An object of the invention is to provide a technique for improving the efficiency of performance regeneration process that is executed on NOx storage reduction catalysts provided in a plurality of branch passages branching from the exhaust passage and reduce emissions of NOx from an internal combustion engine to the atmosphere. The drive signal generator is to be coupled to control switching of a switch included in the power supply to regulate an output voltage of the power supply in response to a sensed output voltage such that the output voltage of the power supply is greater than an input voltage of the power supply. The data objects are converted to a common data format, and are then transmitted to the client.