A welding gun includes a motor, a wire feed mechanism, a power block, a welding tip, a and a cup. The over-shell acts as a force module. The method further enables parsing each record to obtain a wrapper object. The ion metal plasma deposition chamber is evacuated to a first base pressure. At least one detection period is predefined for detecting a signal of a signal source, a differential signal of a pair of signal sources, or a dual-differential signal of three signal sources during at least one clock cycle.