Keyence radar level sensors: the FR-L, and the short-range FR-S01.
¶ What it measures
Liquid level by radar — see Radar Level.
“FR-L” is the long-range family: the FR-LM20 (standard model), FR-LP20 (chemical model) and FR-LS20 (sanitary model). The long-range figures below are for the FR-LM20; check the FR-LP20 and FR-LS20 pages for their materials and connections.
| FR-S01 (short range) | FR-LM20 (long range) | |
|---|---|---|
| Measuring range | Up to 1.5 m (4.9 ft) | Up to 20 m (65.6 ft) |
| Display range | Up to 2 m (6.6 ft) | Up to 25 m (82.0 ft) |
| Accuracy | ±20 mm up to 0.1 m; ±5 mm from 0.1 to 0.3 m; ±1 mm from 0.3 to 1.5 m | ±10 mm up to 0.1 m; ±1 mm from 0.1 to 10 m; ±2 mm from 10 to 20 m |
| Second value in the data | Accumulated level value | Flow conversion value |
| External input | Yes (IO5 switchable to external input) | No |
| Display | Built in | Display part, can be separated from the head |
| Current consumption | 80 mA or less, excluding load | 106 mA or less |
| Ambient temperature | −20 to +55 °C | −20 to +50 °C (−4 to +122 °F), display part combined or separated, no freezing |
| Ingress rating | IP67 (IEC 60529) | IP67 (IEC 60529), Type 4X (NEMA 250) |
| Process connection | G3/4 (20A) | G1-1/2 (40A) |
| Materials | Lens PTFE; packing FKM; joint SUS304; housing PBT | Lens PTFE; internal packing FKM; joint SUS304; housing PPS / PET / PAR |
| Weight | Approx. 170 g | Approx. 600 g |
Common to both:
| Resolution | 1 mm (0.04 in) |
| Detection target | Dielectric constant 2 or higher; target type set as water-based, oil-based or powder |
| Response time | 0.4 s, 1.5 s, 4 s (default) or 10 s |
| Tank pressure | −0.1 to +1 MPa |
| Coupling temperature | −20 to +85 °C |
Accuracy figures are Keyence’s guaranteed values in water with the recommended installation. Measurement may not be possible with some target shapes and environments.
¶ Electrical interface
| Supply | 24 V DC +25 % / −20 % |
| Output | IO-Link (IO2 switchable to IO-Link) |
| Switch outputs | Up to 5; NPN/PNP open collector, selectable; N.O./N.C. |
| Switching output rating | 30 V DC or less, max. 50 mA each, residual voltage 1.4 V or less (at 50 mA or less) |
| Analog output | 0–20 mA or 4–20 mA, max. load resistance 260 Ω |
| Protection | Reverse power connection, power supply surges, output overcurrent and output surges |
| IO-Link | v1.1, COM2 (38.4 kbps), min. cycle time 10 ms |
| Connector | M12, 8-pin on the sensor. For IO-Link, the optional Keyence IO-Link cable converts it to an M12 4-pin male plug for the master |
¶ Notes
- The FR-S01 is the short-range model, with a built-in display.
- Both report detailed diagnostics beyond the measurement: interference, decreased stability, not measurable, learning error, and per-output overcurrent. They are useful in tanks with agitators or foam.
- Only the long-range FR-L supports flow conversion. On the short-range FR-S01 the same data field carries the accumulated level value instead.
- Both report a stability value from 0 to 4. Higher is better; 0 means the level cannot be detected.
- On the IO-Link cable’s M12 4-pin plug, pin 1 is 24 V DC, pin 3 is 0 V, pin 4 is IO-Link, and pin 2 is a control output.
- Set the detection target (water-based, oil-based or powder) to match the tank contents.
- Set the tank bottom distance so the sensor knows where empty is. The settable range is 0–2000 mm on the short-range type and 0–25000 mm on the long-range type.
- Keyence notes that static water can be measured up to the edge of the lens on the FR-S01.
¶ Maintenance
- Watch the stability value. A falling stability value, or a “stability alert” or “interference” flag, with nothing changed in the tank, is the first sign of build-up on the lens or a new obstruction.
- Inspect the lens. Check the PTFE lens for deposits, foam residue or condensation and clean it if needed.
- Run a diagnosis. The sensor has an “execute diagnosis” command, and reports the number of echo peaks it sees and the distance and stability of each. Use this to find false echoes from tank fittings.
- Re-learn the tank. After changes inside the tank (new fittings, agitator, moved sensor), clear and re-run learning so the sensor ignores fixed echoes. Check that the learning state reports available and no learning error.
- Near and far masks. If a fixed object near the top or bottom causes false readings, the near and far mask distances can be set manually instead of automatically.
- Simulation. A simulation mode sets a test current value, or a “no detection” state, so outputs and the controller side can be checked without changing the level.
- Replacing a sensor. Settings are backed up by the IO-Link master’s data storage and restored when a sensor of the same type is fitted.
¶ Using it with a controller
Wiring and configuration live with each controller:
- InteliHive — on an IO-Link port. See Supported Devices.