Modern industrial automation applications demand high performance instrumentation. A well-established technique is to use 4-to-20 mA current-mode transmission (rather than voltage signal) between process sensors and data-processing system elements. This method is less susceptible to the electrical noise problems common in industrial automation and control system applications.
However, modern data-processing components are typically designed for voltage inputs, especially those based on digital technology. The 4-20 mA signals from remote sensors must be converted to voltage level signals, typically 0 to 5 volts, for compatibility with these components.
This conversion is relatively simple requiring only a resistor (Figure 1). Obviously, the accuracy of the current-to-voltage conversion depends upon the precision of the resistor. Riedon precision resistors are ideal for this application: