The input method is the connection method of input analog signal. There are two input methods: Single end and Differential input. For environments where the potential difference between the signal source and the ground and noise components can be ignored, single ended input is suitable. Also, in an environment where the potential difference between the signal source and the ground and the noise component can not be ignored, the differential input is suitable. When differential input is used, the number of usable channels is half of that of single ended input.