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  • New item   Submersible hydrostatic liquid level sensor | level transmitter | RS485 | DC 12–36 V | for water, oil and other liquids | stainless steel probe
    New item   Submersible hydrostatic liquid level sensor | level transmitter | RS485 | DC 12–36 V | for water, oil and other liquids | stainless steel probe 1
    New item   Submersible hydrostatic liquid level sensor | level transmitter | RS485 | DC 12–36 V | for water, oil and other liquids | stainless steel probe 2
    New item   Submersible hydrostatic liquid level sensor | level transmitter | RS485 | DC 12–36 V | for water, oil and other liquids | stainless steel probe 3

    Submersible hydrostatic liquid level sensor | level transmitter | RS485 | DC 12–36 V | for water, oil and other liquids | stainless steel probe

    Code: ES-YWTT1M-RS485
    Inquire about this item
    Price 80.00 € VAT incl.
    ( 66.12 € VAT excl. )

    Submersible hydrostatic liquid level transmitter with RS485 output – for measuring the level of water, oil and other liquids non-corrosive to stainless steel in reservoirs, wells and boreholes. Power supply DC 12–36 V, accuracy 0.5 % FS, ingress protection IP68.

    The measuring range (from 0–1 to 0–200 m H₂O) and cable length are made to order. The cable has a vent capillary for atmospheric pressure compensation.

  • Product description

    Submersible Hydrostatic Liquid Level Sensor / Level Transmitter – RS485, DC 12–36 V, IP68

    The submersible hydrostatic liquid level sensor is designed for continuous liquid level measurement in reservoirs, tanks, wells, boreholes and process systems. The probe sits in the liquid and measures the pressure of the liquid column, then transmits the level value via the RS485 digital interface to a PLC, controller, data logger or SCADA system.

    Sensing element – diffused silicon pressure chip, housing – stainless steel, ingress protection IP68. Power supply – DC 12–36 V (typically 24 V DC).

    Important when ordering:
    this transmitter is made to order – the measuring range (from 0–1 to 0–200 m H₂O) and cable length are selected according to the depth of your tank. As standard, the cable length equals the range (e.g. 0–5 m – 5 m cable). When ordering, specify the maximum liquid depth and the distance to the junction box.
    Output
    RS485 (4 wires)
    Power supply
    DC 12–36 V
    Accuracy
    0.5 % FS
    Range
    0–1 … 0–200 m H₂O

    Application

    The transmitter is intended for applications where the level value must reach the automation system as a digital signal: pumping stations, water intakes, process tanks, sewage and drainage wells. An RS485 line transmits data over hundreds of metres on a single cable and allows several devices to be connected to the same bus.

    Typical tasks:
    • water level measurement in reservoirs, wells and boreholes;
    • level monitoring of process tanks and cisterns;
    • level control of oil or other liquids non-corrosive to stainless steel;
    • pump automation and dry-run protection in the controller;
    • high / low level alarms in a PLC or SCADA system;
    • transmission of level data to a remote monitoring system.

    Operating principle

    The submerged probe measures the hydrostatic pressure created by the liquid column: 1 m of water ≈ 9.81 kPa. The pressure acts on a 316 stainless steel diaphragm, the diffused silicon chip behind it converts it into an electrical signal, and the integrated electronics transmit the level value via RS485. The cable contains a vent capillary – it admits atmospheric pressure to the sensor, so changes in the weather do not affect the reading.

    Engineering note:
    the transmitter is calibrated for a water column. For another liquid, the true level = reading in metres of water ÷ relative density of the liquid (water = 1). For example, for diesel (≈ 0.84) the uncorrected reading would be about 16 % lower than the true level.

    Technical data

    Type Submersible hydrostatic level sensor / transmitter
    Sensing element Diffused silicon pressure chip
    Output signal RS485, digital, 4-wire connection
    Supply voltage DC 12–36 V (typically 24 V DC)
    Measuring range Made to order: from 0–1 to 0–200 m H₂O
    Accuracy 0.5 % FS (standard); 0.2 % FS – on request
    Long-term stability ±0.1 % FS per year
    Temperature drift ±0.02 % FS / °C
    Overload Up to 1.5 times the range
    Medium temperature 0–50 °C
    Measured medium Water, oil and other liquids non-corrosive to stainless steel
    Materials Housing – 304 stainless steel; diaphragm – 316 stainless steel
    Cable Polyurethane, shielded, with vent capillary; length made to order
    Ingress protection IP68
    Probe diameter Approx. 25 mm
    Dead zone ≈ 20 mm from the probe tip (liquid below this level is not measured)
    Mounting Suspended from a cable clamp or fixed via a flange
    RS485 protocol / registers To be confirmed against the supplied documentation (Modbus RTU is not separately confirmed by the supplier)

    Wire assignment

    Wire Function Connect to
    Red V+ power supply Power supply +24 V DC
    Black V− power supply (0 V) Power supply 0 V
    Blue RS485 A Controller RS485 A
    White RS485 B Controller RS485 B
    Shield Cable shield Earthed at one end only – on the controller side

    Wiring diagram: transmitter → power supply → PLC via RS485

    RS485 wiring diagram of the submersible level transmitter
    ☝ Click the diagram to open an enlarged version.
    Why it is done this way – explanation by diagram numbers:
    1. ① The probe is suspended above the sludge: a silted-up diaphragm no longer follows the level. Because of the ≈ 20 mm dead zone, liquid below the probe tip is not measured.
    2. ② A stabilised 24 V DC supply sits in the middle of the transmitter's operating range (12–36 V), so the voltage drop along a long cable does not push it out of limits.
    3. ③ RS485 is a differential line, but the transmitter V− and the controller GND must be connected. Without a common zero, the difference between earth potentials can exceed the permissible value and communication becomes intermittent.
    4. ④ The shield is earthed at one end only. If earthed at both ends, an equalising current flows through the shield and itself becomes a source of interference.
    5. ⑤ The 120 Ω termination resistor is fitted only at the physical ends of the bus, not at every device. Without it, long lines suffer from reflections and communication errors.
    6. ⑥ The end of the vent capillary is left open in a dry box: it admits atmospheric pressure to the sensor. If the capillary is sealed or gets wet, the reading starts to "drift" with the weather, and condensation can damage the sensor.
    A and B labelling varies: some manufacturers call A D+, others D−. If there is power but no communication, first swap the blue and white wires – this will not damage the transmitter.
    ⚠ The diagram is for guidance only. Check the wiring against the supplied transmitter documentation and the controller manual. Installation must be carried out by a qualified electrician, who is responsible for it. UAB „Elektrotechnikos sprendimai“ accepts no liability for the connection or any possible errors.

    RS485 communication setup

    Before connecting to the PLC, check:
    • the protocol and register map according to the supplied documentation;
    • the device address and data transmission speed (baud rate);
    • parity, data bit and stop bit settings;
    • the scaling and units of the transmitted value;
    • termination resistors at the ends of the bus.
    RS485 ≠ automatically Modbus RTU:
    RS485 defines only the physical interface. The supplier specifies "RS485 communication" but does not separately confirm Modbus RTU. Confirm the protocol against the transmitter documentation or ask us before ordering.

    Installation

    • The probe must always remain submerged – suspend it below the minimum level, but above the sludge.
    • Do not lay the probe on the bottom and do not install it beneath an inflowing liquid stream.
    • Secure the cable with a clamp to the tank or borehole head – an unsecured cable slips, and the zero "drifts" with it.
    • In boreholes and tanks with an agitator, it is best to lower the probe through a separate stilling tube.
    • Leave the end of the vent capillary open in a dry, ventilated junction box – do not seal or submerge it.
    • Shorten or extend the cable only in a dry box above the liquid.
    ⚡ Safety notes:
    before lowering the probe into a borehole or well, disconnect the pump so that no one can switch it on accidentally. Never enter wells alone – hazardous gases may accumulate in them. The transmitter has no Ex marking, so it must not be used in tanks containing petrol, solvents or other explosive media.

    Selecting the measuring range

    Choose the range according to the maximum actual liquid column above the probe, leaving a small margin. An oversized range reduces practical accuracy: 0.5 % FS of 30 m is 15 cm, while of 5 m it is 2.5 cm.

    Advantages and limitations

    Advantages
    • Digital RS485 output – one cable for several devices.
    • Range and cable selected for your site.
    • IP68, 304 housing and 316 diaphragm.
    • Vent capillary compensates for atmospheric pressure.
    • No moving parts, unlike float switches.
    • Wide 12–36 V DC supply range.
    Limitations
    • The reading is affected by liquid density.
    • Medium temperature – up to 50 °C.
    • Not suitable for corrosive liquids or explosive media.
    • Protocol and registers must be matched with the controller.
    • For a simple PLC with an analogue input, the 4–20 mA version is more convenient.
    ☝ Elsprendimai.eu recommends:

    Frequently asked questions (FAQ)

    Which range should I order?
    Based on the maximum liquid depth above the probe, with a small margin. For example, a 0–5 m transmitter suits a 3.5 m tank. For a deeper borehole, choose the range according to the water column above the probe, not the full depth of the borehole.
    Does the transmitter work with Modbus RTU?
    The supplier specifies RS485 communication but does not separately confirm Modbus RTU. Check the protocol and registers against the supplied documentation or ask us before ordering.
    Can it be used in an oil or diesel tank?
    Yes, provided the liquid is non-corrosive to stainless steel and the cable sheath, and the reading is corrected for density. Not in tanks containing petrol or other explosive media – the transmitter has no Ex marking.
    Why does the reading "drift" even though the level is not changing?
    Most often the end of the vent capillary is sealed or damp, the cable is not secured, or the probe is sitting in sludge. Check the installation according to the "Installation" section.

    Documents and sources

    Technical data – according to the supplier's specification and wiring diagram, checked on 2026-10-17. Transmitter documentation with communication parameters is available on request.

    RS485 level measurement for automation

    Submersible hydrostatic transmitter with RS485 output, IP68 and a range matched to your tank. Tell us the liquid, depth and cable length – we will select the right version and power supply.

    Illustrative image may have been created using AI. The appearance of the product may differ slightly from the image shown. Please refer to the technical specification.

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