What Is an Analog Inductive Sensor? Types and Selection Criteria
An analog inductive sensor is a proximity sensor that measures the distance to a metal target without contact and gives a proportional voltage or current signal.
An analog inductive sensor is a proximity sensor that measures the distance to a metal target without contact and gives a continuous voltage (e.g. 0–10 V) or current (e.g. 0–20 mA) signal proportional to that distance. While a switching-output inductive sensor only reports "metal present/absent", an analog sensor reports where the target is within its measuring range. It is therefore used where continuous measurement is needed, such as monitoring the position of a metal part, sheet thickness or warping, or shaft run-out. Its signal cannot be read by a PLC digital input; an analog input is required.
Types
- Cylindrical housing: M12, M18 and M30 threaded housings; the larger the housing, the wider the measuring range.
- Square housing: 40 × 40 mm housings are screwed onto a flat surface and come in different depths.
- By output signal: Models with voltage only, current only or both. All models in the catalogue give 0–10 V and 0–20 mA outputs together.
- By connection type: Fixed cable or M12 connector.
Selection criteria
- Measuring range: The target's movement must stay within the sensor's measuring range. The range does not start at zero (e.g. 0.8–4 mm); below the lower limit and above the upper limit the output is not meaningful.
- Housing and mounting: In the Lanbao LR series, N in the model code indicates non-flush mounting; these models need a metal-free zone around the sensing face. Sensors placed side by side are spaced at the distance given in the datasheet so they do not affect each other.
- Target material and size: The output curve is given for a steel target. With stainless steel, aluminium, brass and copper the curve changes and the range shortens; for these metals, scale with the actual target. The target should be at least as wide as the sensing face.
- Output signal: Use the voltage or current lead according to the analog input that will read it. The minimum load resistance for the voltage output and the maximum for the current output are in the datasheet.
- Response frequency: With fast-moving or vibrating targets, the signal must be able to follow the motion. In the catalogue, cylindrical models are 100 Hz and square models 50 Hz.
- Linearity and temperature drift: Where measurement precision matters, compare the linearity, repeatability and temperature drift values in the datasheet.
Common mistakes
- Connecting to a digital input: On a digital input the analog signal just flips to 0/1 at an arbitrary threshold; the position information is lost.
- Reading a 0–20 mA output with a 4–20 mA input: Values in the lower range appear as a broken line or an error; set the input range to match the sensor output.
- Embedding a non-flush model in metal: The surrounding metal adds to the signal and the curve shifts.
- Using a steel-scaled curve on another metal: With an aluminium or copper target, the distance read differs from the real one.
Relevant standards
Requirements for proximity sensors with analogue output are in IEC 60947-5-7 (current edition 2024; in Europe EN IEC 60947-5-7:2025). It builds on the same product scope as IEC 60947-5-2, which covers switching-output proximity sensors.
Analog inductive sensors in the Welibaba catalogue
All 5 active products in the Analog Inductive Sensors category are Lanbao; all are supplied with 10–30 V DC and give 0–10 V and 0–20 mA outputs together (October 2026):
| Model | Housing | Measuring range | Response frequency |
|---|---|---|---|
| LR12TCN04LIUM | M12 | 0.8–4 mm | 100 Hz |
| LR18TCN08LIUM | M18 | 1.6–8 mm | 100 Hz |
| LR30TCN15LIUM | M30 | 3–15 mm | 100 Hz |
| LE40TSZSN15LIUM-E2 | 40 × 40 × 66 mm | 3–15 mm | 50 Hz |
| LE40TXZSN15LIUM-E2 | 40 × 40 × 120 mm | 3–15 mm | 50 Hz |
To read the signal see Analog Input Modules; for presence detection only, see the switching-output models in Inductive Sensors.
Frequently asked questions
What is the difference between an analog inductive sensor and a standard inductive sensor?
A standard (switching-output) inductive sensor turns its output on or off when the target enters the sensing distance. An analog inductive sensor gives a voltage or current that changes continuously with the target's distance across the measuring range; the PLC calculates the distance from this signal.
Should I use the 0–10 V or the 0–20 mA output?
Use the one your analog input card reads. If the cable is long or the environment is noisy, the current output is more stable; for short connections inside a panel, the voltage output is enough.
Can an analog inductive sensor measure aluminium or stainless steel?
Yes, but the output curve differs from that for steel and the measuring range is shorter. Scale with the actual target material and check the material correction information in the datasheet.
Why does the measuring range not start at zero?
When the target comes very close to the sensing face, the signal no longer changes linearly with distance. The manufacturer therefore gives the linear region (e.g. 3–15 mm) as the measuring range; the target's movement must stay within it.