shelleycat:
The female 9 way d-type, which I understand is part of a USB-RS232 converter is NOT compatible with your arduino. Stop connecting it.
The output is +10 to -10V, which might blow the Arduino input pins.Try this:
COM to Arduino ground (0V).
NO to an Arduino digital input pin. Any will do (but not the dedicated serial 0 or 1).Set the Arduino input pin to INPUT and write the value to HIGH. This will turn on the internal pull up. So the value read
will be 1 when the bucket is not tipped, and 0 when the bucket tips.
Yep, that's the way to do it. The gauge is providing you with a 'dry contact' so direct connection to arduino ground and a digital input pin with the pin's internal pull-up enable will work fine. However if it's a long run of cable from the gage to the arduino I would be sure to use shielded cable. You might also have to do some software debouncing on the pin's readings.
Lefty