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Each flow meter has a positive (+), negative (-) and signal (0) terminal.  The type of connector and pinout used by the coffee machine / flow meters varies by manufacturer and model.  Flow meter cable plus adapters are available for the following variations

See https://flowcoffee-co-nz.atlassian.net/wiki/spaces/FGCI/pages/461242401/Espresso+machine+knowledge+base#Flow-meter-connection-variations for an overview of the different types of flow meter connections found in common makes/models of espresso machine.

GDS 207 connector compatible

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