Temperature transmitter (4–20 mA vs. 0–10 V): 3-step selection

It's a common nightmare in industrial control circles: when you purchase a temperature transmitter, its output signal fails to connect to the PLC. The root cause is simple—there's a mistake in selecting between 4–20 mA and 0–10 V signals.

Although both are standard analog signals, their applications differ vastly. Today, we'll use three key dimensions to help you make the right choice in just five minutes.

Step 1: Check the transmission distance

This is the most critical criterion for judgment.

The 4–20 mA signal represents a current value unaffected by line resistance. Even over distances of 500 meters or more, the received current remains stable. Furthermore, the 4 mA level serves as a "live zero point" —detected at 0 mA immediately indicates a wire breakage fault, doubling troubleshooting efficiency.

The 0–10 V range represents a voltage signal, with greater voltage drop occurring as the wiring length increases. Beyond 30 meters, voltage attenuation and electromagnetic coupling interference become pronounced. When cables are routed near frequency converters or high-power motors, reading fluctuations are commonplace.

In short: For distances exceeding 30 meters, simply select 4–20 mA. For short distances inside control cabinets, 0–10 V is also suitable.

Step 2: View the backend device interface

You can't simply choose whatever you want; it depends on which types of analog input modules the PLC or DCS supports.

Most domestically produced low-cost PLCs and temperature controllers only offer 0–10 V input channels, making direct use of 0–10 V transmitters the most straightforward solution. However, if the backend system requires current input but only voltage-output transmitters are available, an additional signal conversion module must be installed—resulting in extra costs and space requirements.

Conversely, if both backend components are compatible and there is significant interference at the site, prioritize using the 4–20 mA signal.

Step 3: Assess the industrial site environment

In chemical workshops, steel mills, and power systems, frequency converters, welding machines, and high-power switching equipment are often densely installed, resulting in severe electromagnetic interference. The 4–20 mA current circuit exhibits significantly stronger noise suppression capability against induced noise compared to the voltage circuit, yielding cleaner signals.

The setup includes a laboratory, test bench, and well-controlled environment with minimal electromagnetic interference; it fully supports 0–10 V voltage signals while featuring a simple circuit design and lower cost.

Summary: 3-Step Decision-Making Method

There's no absolute right or wrong when selecting a signal type—only suitability matters. By following the three steps above, you'll rarely make mistakes in signal selection.

For bulk procurement of temperature transmitters (available in all models: 4–20 mA, 0–10 V, or RS485), please contact Weilian Fengran Sensing Technology for free technical selection assistance.