This device is used for converting standardized analog signals (0(4)-20mA, 0-10V, 0-5V) for example 4-20mA input to 0-10V output. The device has to be ordered for the specific conversion and can not be changed later.
The signal converter is used in cases where the measurement device or transmitter analog signal type is not corresponding to the input of the processing unit. For example, you have a conductivity transmitter with 4-20mA output, but you have a Siemens 1200 PLC with only analog 0-10V signal input. Using this converter the 4-20mA signal is converted to 0-10V analog signal and it is cheaper then buying an analog input module for the PLC. Plus it is a 3 point galvanic isolator itself, which makes 3500kV isolation between the input, output and power supply.