AM-D-DFM Doppler Flow Sensor

This is a sensor, not a meter. It measures how fast the water moves from the Doppler shift of the particles and bubbles carried in it, reads depth with a pressure sensor and water temperature with a second sensor, and answers on RS485. A totalizer, RTU or logger asks for those three numbers at the interval you set and does the flow arithmetic itself — which is what makes it suit open channels, sewers and irrigation intakes running on battery or solar power.

The boundary is that you supply the host. There is no display and no 4–20 mA output: a PLC that wants a current loop, or an operator who wants to read a number off the instrument, needs the AM-DFM — the complete Doppler unit with a screen and its own 4–20 mA and relays — and the two model names differ by a single letter. It also needs 15 cm of water over the sensor, and enough suspended solids in the water to reflect the pulse.