This submersible level sensor is simple to use, just put the probe into the bottom of a water tank, a river, a deep well, etc.
Atmospheric Compensation: The cable includes a vent tube; it must be kept open to the atmosphere (not sealed in a box) to ensure accurate readings.
How to choose a right product?
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Measuring range = level height (if the maximum level height is 4m, you should choose 4m or 5m etc, you should not choose a smaller range like 3m).
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Output signal:
4-20mA (2 wires）
0-10V ,0-5V, 1-5V (3 wires)
0.5-4.5V (3 wires)
RS485 Modbus (4 wires) -
Power supply:
DC24V for 4-20mA, 0-10V, 0-5V, 1-5V, RS485 (DC10-30V wide range of voltage supply)
DC5V for 0.5-4.5V, 0-3.3V -
Cable length: choose the cable length according to your needs (can be customized).
Product Description
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The QDY30A is a submersible water level sensor, its 304 & 316 stainless steel and hermetically sealed housing make it suitable for most industrial liquids.
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The welded housing is tested in-house via a helium leak tester to ensure proper protection. The ventilation tube in the cable automatically compensates for changes in atmospheric pressure above the tank.
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The conductors of the cable are also well isolated from the outside environment to keep the level sensor operational for long-term use.
How to use with RS485: hardware
Termination: A 120 Ohm resistor may be needed between A and B if communication is unreliable.
| Wire color | Function |
|---|---|
| Red | V+ |
| Green | V- |
| Blue | A |
| Yellow | B |
How to use with RS485: software
Control is achieved via RS485 using Modbus RTU commands (Function Code 03 to read) to retrieve data, usually outputting level in mm.
Communication Settings: Default is typically 9600 baud, 8 data bits, 1 stop bit, no parity, and Address 1.
Read Command (Hex): To read the level, send: 01 03 00 00 00 01 84 0A (Address 01, Function 03, Register 0000, Quantity 1, CRC).
Sensor Response: The sensor returns data (e.g., 01 03 02 00 64 39 A2) where 00 64 (hex) is the level in mm (100mm).
Data Processing: Convert the Hex response from the “holding register” to decimal to obtain the water level in mm.
Addressing: You can change the device address by writing to specific registers, allowing multiple sensors on one RS485 bus.