The DiagBelt system is the diagnostics device for assessment of a technical condition of conveyor belts. The following paper concerns the magnetic module dedicated for monitoring of belts with steel cords. The system allows scanning of belts with different cord diameters and their density. The speed of the belt also may vary depending on the operating conveyor. Additionally, the system user can change measurement sensitivity and the distance between the measuring probe and the cord. The measurement allowed to determine values of these parameters of which test results are the most reliable. In practice, this enables faster and more accurate assessment of a belt condition, which plays a significant role in the planning maintenance operations. It has a good impact on the continuity of belt operation and belt conveyors reliability. Therefore, it improves the reliability of the whole mining transport system.