What is the best method to verify a 4-20 mA signal?

To verify a 4-20 mA signal effectively, placing the Digital Multimeter (DMM) selector to the mA mode and connecting the leads in series with the circuit is the best method. This approach allows for a direct measurement of the current flowing through the loop.

The 4-20 mA current loop is a standard for transmitting analog signals in many industrial applications, where 4 mA typically indicates a zero reading and 20 mA represents full scale. By introducing the DMM in series, the instrument can accurately display the current value being sent, enabling the technician to confirm that the signal is within the expected range.

Furthermore, measuring in series with the circuit minimizes the risk of altering the current flow. It provides an accurate representation of the signal without introducing resistance that could affect the performance of the instrumentation loop.

Other methods, such as using an oscilloscope, may not be suitable for a continuous current signal as they are primarily designed for voltage signals and could require additional setup to interpret a current signal effectively. Checking voltage across the circuit does not provide a direct current reading required to verify the 4-20 mA signal. Similarly, a clamp meter is typically used for non-intrusive measurement and might not be