The utility model discloses a diagnostic device is gathered to modularization, including box -like shell and controller, include still that converter and a plurality of have the information acquisition module of different functions, be equipped with on the shell the first mount pad of converter with the second mount pad of controller, be equipped with first external tapping in the first mount pad,but converter plug ground is connected on the first external tapping of shell, it corresponds to be equipped with a plurality of on the converter information acquisition module's second external tapping, but information acquisition module plug ground is connected on the second external tapping of converter, the controller with be equipped with guiding mechanism between the first mount pad. The utility model discloses a but the information acquisition module and the converter of plug equipment, can make up in a flexible way and form multiple diagnostic tool, reduce field force's the burden ofcarrying, increased the suitability of product.