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Colour independent
Detection is based on the return of sound rather than visible-light reflection, helping with changing colours and finishes.
ifm · Position & Level Sensing
ifm Ultrasonic Sensors
Contactless position, distance and level sensing for targets that are difficult for optical technologies. Ultrasonic sensing is largely independent of target colour, transparency and optical reflectivity, with current ifm routes spanning compact M18 housings through long-range M30 and robust full-metal designs.
Up to 8 mM18 & M30Digital / analogueIO-Link by modelDiffuse & retro-reflective
Maximum family rangeUp to 8 mCurrent M30 route
Housing routesM18 / M30Plus cube and full-metal options
OutputsSwitch / analoguePNP/NPN and analogue by model
Digital setupIO-LinkAvailable on current selected variants
Where sound solves the sensing problem
Reliable detection when colour, transparency or optical reflectivity changes
ifm positions ultrasonic sensing for targets and surfaces where conventional optical detection can become application-sensitive. Selection still depends on range, blind zone, target geometry and the acoustic environment.
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Transparent targets
Suitable routes are available for transparent bottles, glass and other targets that can challenge conventional photoelectric sensing.
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Distance values
Selected sensors provide continuous distance information through analogue output or IO-Link rather than only an on/off state.
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Irregular surfaces
The wider acoustic beam can be useful for uneven, structured or irregular targets where a pinpoint optical spot is undesirable.
Application routes
ifm ultrasonic sensors in the system architecture
The strongest applications are those where non-contact sensing is needed and the target provides a usable acoustic return.
Liquids and bulk solids without probe contact
Continuous non-contact measurement can be used for open tanks, bins and vessels when the acoustic path and target surface are suitable.
Transparent bottles, glass and changing colours
Ultrasonic sensing avoids dependence on the optical transparency or colour of the target, provided the target geometry returns sound reliably.
Roll diameter and remaining material
Monitor changing roll diameter on paper, film and web handling applications without readjusting for colour or reflective coating changes.
Angled or sound-absorbing targets
When a diffuse sensor cannot obtain a stable return echo, a retro-reflective ultrasonic route can detect interruption of a defined reflected signal.
Measurement principle
Measure the echo time of an ultrasonic sound pulse
The transducer sends an ultrasonic burst and then receives the echo returned by the target. The elapsed time is converted into distance using the speed of sound. In simplified form, distance is calculated as d = c × t / 2.
Diffuse sensingThe target itself returns the sound. The blind zone and target orientation must be considered.
Retro-reflective sensingA defined reflector returns the sound; interruption of that path is evaluated for difficult target surfaces or angles.
Temperature compensationCurrent ifm ultrasonic sensors use integrated temperature compensation to stabilise the distance signal as ambient temperature changes.
Response curveUse the product-specific sound / response curve to confirm beam width, target size and sensing geometry.
Housing and range selection
Ultrasonic selection by distance, mounting space and environment
These are family-level selection routes from ifm's current ultrasonic portfolio. Exact switching ranges, blind zones, outputs and materials must be confirmed on the selected order number.
M18 short body
Up to 1,200 mm
Compact 60 mm M18 housing route for general position and level sensing.
- PNP / NPN variants
- Analogue variants
- IO-Link variants
M18 long / robust routes
Up to 2,200 mm
Longer M18 housing options extend the sensing range while retaining an industry-standard threaded format.
- 98 mm family housing route
- Plastic or stainless options by model
- Retro-reflective versions within the broader M18 portfolio
M30 long range
Up to 8,000 mm
Use the larger M30 sensing head where the application requires substantially longer stand-off distance.
- Stainless steel housing route
- Digital / analogue outputs by model
- IO-Link variants
M18 cube style · up to 1,200 mm
A space-saving alternative with an M18 threaded nose or through-hole mounting options, depending on the selected model.
Full-metal · up to 2,500 mm
All-metal stainless steel sensing-face variants are intended for increased robustness in harsh environments. Exact compatibility still depends on the medium, mounting and environment.
Family-level data
Key technical data
Use these values to narrow the technology and housing route. Final specification must be taken from the selected ifm order-number datasheet.
Sensing range is not the only selection criterion
Blind zone, target size, beam width, orientation, speed, mounting distance to neighbouring ultrasonic sensors and environmental airflow can determine whether a nominally suitable range will work reliably.
Measurement principleUltrasonic time of flight
Current family maximum rangeUp to 8,000 mm
Housing familiesM18 short, M18 long, cube, M30, full-metal
Output routesDC PNP / NPN, analogue, IO-Link by model
Temperature compensationIntegrated on current family positioning
Blind zoneProduct specific; critical for diffuse sensing
Target orientationApplication dependent; smooth diffuse targets should face the sensor appropriately
Materials / IP ratingModel dependent
Engineering checks
Confirm the acoustic application before choosing the order number
Ultrasonic is robust against many optical variables, but it is not immune to target and environmental constraints.
Blind zone
Diffuse ultrasonic sensors need a minimum distance in front of the sensing face to generate, receive and evaluate the sound signal.
Target material & angle
Sound-absorbing materials or surfaces that deflect the echo away from the sensor can reduce reliability. Retro-reflective sensing may be a better route for some targets.
Air turbulence
Strong wind, compressed-air flow or cooling fans can disturb sound propagation. Shield the acoustic path where necessary.
Target speed
Diffuse ultrasonic switching is generally not the first choice for very high-speed targets; confirm the product switching frequency against the machine cycle.
Target size
Very small targets can be better suited to laser or photoelectric sensing. Use the sensor's response curve to confirm the usable detection zone.
Crosstalk
Multiple ultrasonic sensors mounted too close together can interfere. Respect the product installation spacing and synchronisation guidance where applicable.
Small openings: ifm identifies the E23000 sound tube as an accessory route for focusing the sound beam where precise detection through small openings is required.
Technology choice
Ultrasonic or another ifm sensing technology?
Ultrasonic is valuable when optical target characteristics vary, but another technology may be stronger for tiny targets, very high switching speeds or materials that absorb sound.
| Application need | Technology route to review | Why | Key check |
|---|---|---|---|
| Transparent / different-colour objects | Ultrasonic | Detection is not based on visible-light reflectivity or colour. | Target must return a usable acoustic echo. |
| Open tank liquid / bulk-solid level | Ultrasonic | Non-contact continuous distance measurement. | Foam, vapor, surface geometry, turbulence and range. |
| Tiny high-speed target | Photoelectric / laser route | Smaller spot and higher switching speed can be advantageous. | Target colour/reflectivity and background. |
| Sound-absorbing or angled target | Retro-reflective ultrasonic or alternative optical route | Diffuse acoustic echo may be weak or deflected. | Reflector position and available installation geometry. |
| Metal target at short range | Inductive | Simple short-range metal detection may not need distance measurement. | Target material and required sensing distance. |
Requirement capture
Inputs required to select the right ultrasonic sensor
Share the application geometry rather than only asking for a distance range. It materially improves sensor and mounting selection.
Target / mediumLiquid, solid, transparent object, film, roll, irregular surface, etc.
Required distanceMinimum and maximum target distance, not only nominal range.
Target dimensionsSize, shape, angle and direction of movement.
FunctionPresence, switching point, window, level or continuous distance.
Output / controlPNP, NPN, analogue, IO-Link and PLC / IO-Link master.
EnvironmentTemperature, airflow, contamination, washdown and mounting constraints.