The frequency meter adopts high-performance 32-bit ARM cotex-m3 processor as the core of data processing and control, and USES programmable logic chip to design precision frequency sampling circuit, as well as waveform shaping circuit built by analog circuit. With 6-bit digital tube display and automatic range switching, the frequency of any waveform of 0.1hz ~4M can be measured with an accuracy of 0.1hz. The rs-485 communication interface supports the standard modbus-rtu communication protocol. The installation mode is industrial grade cabinet.