LI-7700 sensor on my sites showing a unexpected NAN after three days after starting the sensor and this NAN also increases when the time progresses and after 6-7 days all the LI-7700 data is full of NAN. When we put off the sensor power and on again, the sensor starts recording the correct value but after three days this event again occurs and we have to repeat the sensor power on & off process. Why this is happening? and what is the solution?
Howdy Amit
Probably because there is no numerical value to be shown. NAN shown on screen for most computing devices means Not A Number.
Soluiton? Check the algorithm and the measurement procedure critically. NAN mostly means that the instrument registers a very very large number like the one you get by dividing unity by zero. In Excell this is indicated by DIV/0. With other software it becomes NAN.
A way to check out whether Licor has sold you rubbish is to put your LI-7700 in the lab under a (rather) constant light source continuously or in a cycle of 12h light/12h darkness and wait for three days (or more). Try to log the data output electronically if possible, makes life easier.
If you get NANs without anything changing in the environment of the instrument, your LI-7700 has a malfunction. If it is still under warranty Licor should send you a new one. If warranty has expired Licor made a good deal, but will probably lose you as a (future) client.
Happy hunting,
Frank
