Jim Mimlitz

Jim Mimlitz, SCADAmetrics

When interfacing an open-collector pulse output signal from a flow meter to an EtherMeter, it can sometimes be necessary to provide an electronic isolation & amplification buffer between the flow meter and the EtherMeter.

For example — if the open-collector does not have sufficiently low impedance when it is in the closed state (or if the open-collector does not have sufficiently high impedance when it is in the open state), then the EtherMeter might not detect the pulses.

One solution is to add an interposing solid-state relay into the circuit to provide isolation and amplification.

The diagram below illustrates the details.  Click on the image to zoom in.

Important Note: in the circuit illustrated below, 3.2 milliamps will pass through the meter’s open-collector circuit when closed. Please ensure that 3.2 milliamps does not exceed the specified maximum current capacity of your open-collector pulse circuit!

 

Pulse Isolation and Amplification Circuit.

Jim Mimlitz

About Jim Mimlitz

Licensed Professional Electrical Engineer @ SCADAmetrics. Specialties: Connecting Flow Meters with SCADA, Telemetry, and Building Automation Systems. Electronic Circuit Design, Software Development.

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