SJ5780-300 Bidirectional scanning contour measuring instrument is a large-range, high-precision active scanning comprehensive contour measuring instrument. The instrument X-axis, Z-axis with independent motion system, the use of advanced two-axis linkage motion control algorithms, can be realized X, Z dual-axis linkage scanning, measuring stylus in the surface of the workpiece to do profiling scanning (active scanning), not only to maintain a constant measuring force, but also to ensure that a large number of steep slopes through the ability of the workpiece leveling operation is simple, and at the same time to avoid chipping the needle, hanging pin and other issues. It can scan continuously over a wide range of full scale and has a continuous slope climbing capability of hundreds of millimeters, which is very suitable for measuring a wide range of steep slopes, and large workpieces can be easily measured without turning or tilting adjustments.