Irrometer Watermark with Watermark Voltage Adapter (200SS-VA) (6”, 12”, 24”)

Key Specifications:

Apples to both Standard (SR) series and Low Tension (LT) series of the Irrometer Watermark.

Wiring (to Block Controller via Sensor Adapter):

• Use green pair of cables to connect irrometer watermark to watermark voltage adapter.

• The table below then shows how to connect watermark voltage adapter to the Verdi Sensor Adapter (provides route to the Verdi block controller).

Wiring (to MicroBlock Controller):

• Use green pair of cables to connect irrometer watermark to watermark voltage adapter.

• The Watermark Voltage Adapter should be shipped with the plug that interfaces with the MicroBlock Contoller’s S1 or S2 ports. Connect the terminals and assign the correct sensor to the correct sensor port in software.

Troubleshooting WATERMARK soil moisture sensor readings

Reading stays at the wettest value

If the sensor reads near 0–5 cb continuously, first confirm the soil is actually saturated. A healthy WATERMARK sensor in free water should read about 0–5, so a very low reading can be normal immediately after heavy irrigation or in waterlogged soil. If the soil is not saturated, a constant near-zero reading can indicate a short in the wiring or water intrusion in a splice or connector.

Reading stays at the driest value

If the sensor is stuck at a maximum dry reading, this usually indicates an open circuit, such as a disconnected sensor, broken wire, failed splice, pulled lead, or poor terminal connection. IRROMETER specifically notes that a max-dry reading commonly points to broken or poor wiring. A poorly installed sensor that has lost good contact with the soil can also appear falsely dry.

What “broken or disconnected” looks like

For most WATERMARK readers, a broken or disconnected sensor appears as off-scale dry / max dry / open circuit rather than as a valid soil moisture value. On IRROMETER’s 200SS-SDI adapter, open or short conditions are reported as 255, which is a fault code rather than a real soil moisture reading.

Reading does not change after irrigation

If the reading stays dry even after irrigation, the sensor may have lost contact with the surrounding soil. IRROMETER notes that the sensor depends on a tight bond with the soil; if it is “sitting in the hole,” it may not absorb and release water properly. Reinstalling the sensor with good soil contact is the usual fix.

Quick field checks

Inspect all splices, terminals, and cable runs for cuts, chew damage, corrosion, or loose connections. If possible, isolate the field wiring from the sensor to determine whether the fault is in the cable run or at the sensor. For a bench test, IRROMETER recommends removing the sensor, soaking it in water, confirming it reads about 0–5, then air-drying it for 30–48 hours and confirming the reading rises to 150+, then re-wetting it to verify it drops back below 5 within about 2 minutes.

Recommended interpretation

Treat a reading as a likely fault when it is persistently at the extreme dry end and does not respond to irrigation, especially if nearby sensors do respond normally. Treat a very low reading as real saturation only if field conditions support it; otherwise, check for a wiring short.

If you want, I can turn this into a shorter Verdi-style customer-facing docs section with wording like “Issue / Likely cause / What to do.”

Additional Notes:

• Watermark LT series information: https://www.irrometer.com/pdf/109.pdf 

• Watermark SR series information: https://www.irrometer.com/pdf/105.pdf

• Watermark sensor adapter information: https://www.irrometer.com/pdf/405.pdf