As the new design of the laser marking machine function increases, the degree of automation is high, so the new design before and after the laser marking machine operating panel, the current value, that is, the current value of the bus and the negative bus current value, the two current Value through a certain resistance after the resistance into a voltage value, and then through the conversion circuit, that is, the bus voltage on the bus through the same amplifier, the negative bus voltage through the reverse amplifier, access TLV1544A / D converter, the Analog signal into a digital signal, and then access the 89C52 P1 port for processing.