Verified 2026-11
dfrobot RS485 Fluorescence Dissolved Oxygen Sensor (Freshwater)
IP68 optical dissolved oxygen probe that returns 0-20 mg/L over RS485 Modbus-RTU from a 10-30 V supply, no membrane or electrolyte to replace.
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Part & documents
| Source | www.dfrobot.com/product-3008.html → |
|---|
Pinout
4 pads, as the vendor numbers them.
| # | Name | Function | Signals |
|---|---|---|---|
| 1 | VCC | supply positive, DC 10-30 V, brown wire | |
| 2 | GND | power ground, black wire | |
| 3 | 485-A | RS485 data line A, yellow wire | |
| 4 | 485-B | RS485 data line B, blue wire |
Buses
| Bus | Signals | Pins | Voltage | Note |
|---|---|---|---|---|
| RS485 ×1 | A, B | 485-A, 485-B |
Power
| Input | DC 10-30 V (brown VCC wire) |
|---|
Notes
The vendor names its pads by wire colour and prints no pad numbers; the 1-4 sequence is the order of its own pinout table and is stated as such. The Modbus slave address defaults to 1 (vendor FAQ) and no I2C device exists, so addresses is empty. No baud rate is published on the product page or the wiki - the FAQ mentions that a wrong baud rate is a cause of no replies without ever giving the value - so none is recorded. No schematic is published, so the reference circuit is limited to the bus practice the FAQ states.
AI context
Dense context for pasting into a model prompt — addresses, pinout, voltages, tolerances and the vendor's reference circuit.
PART: DFRobot RS485 Fluorescence Dissolved Oxygen Sensor, freshwater version, SKU SEN0680 - a probe on a 5 m cable, IP68, 0.6 MPa pressure rating, corrosion-resistant plastic casing. It measures by fluorescence quenching rather than with an electrode or electrolyte, so there is no membrane or fill solution to service. The vendor names no silicon part number, so there is no part and no data sheet. ADDRESSES: RS485 Modbus-RTU slave, factory default address 1 - the vendor states this in its FAQ. No I2C device is present, so the I2C address list is empty. PINOUT: four wires, and the vendor numbers none of them - it identifies each by colour. The entry's 1-4 are the vendor's table row order: 1 brown = VCC, DC 10-30 V; 2 black = GND; 3 yellow = 485-A; 4 blue = 485-B. SUPPLY: DC 10 to 30 V, 0.2 W. That is a 12/24 V field bus supply, not a 5 V logic rail - it cannot be powered from a microcontroller board's regulator. MEASUREMENT: 0 to 20 mg/L and 0 to 200% saturation; error +/-3% FS and +/-0.5 C at 25 C; resolution 0.01 mg/L, 0.1% and 0.1 C; response time 60 s or less; temperature compensation is built in; operating temperature 0 to 40 C; fluorescence film life is one year under normal use. LOGIC LEVEL: none. RS485 is a differential bus, so there is no TTL logic level to match, and no absolute maximum for the data lines is published. REFERENCE CIRCUIT: the vendor publishes no schematic. Its FAQ prescribes the bus practice: add a 120 ohm terminating resistor when the run is long or several devices share it, feed the supply close to the device, and add an RS485 repeater rather than stretching the cable. TRAPS: (1) Every unit ships at Modbus address 1, so two probes on one bus collide until one is re-addressed. (2) Both the polling interval and the response timeout must be longer than 200 ms or replies are missed. (3) A and B reversed is the vendor's first-listed wiring fault. (4) The sensing film is a consumable with a stated one-year life, so a probe that reads low after a year is worn, not broken. (5) The freshwater version carries no salinity compensation - the seawater sibling SEN0681 is the one for marine use.
Provenance
Every figure on this page was read from the 2 sources below and last checked on Nov 2, 2026.