Bill,
Sorry about the links and glad you found the info anyway. I've since read that 4-20mA loop-powered circuits are an instrumentation standard. Equipment for the monitor/alarm side should also therefore be available, but these seem to be custom to the measurement parameter itself, built for multiple inputs, of backplane/card construction for rack mount and probably expensive, etc.
The detector itself has a display will indicate a deficient O2 range (<19%) which is good, but no numbers and no alarm if you are interested in those. So , a Radio Shack project? What are your thoughts.
Look forward to hearing if you get one of these.
Paul
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