Monitoring humidity in Nagios with a Watchport sensor is very similar to monitoring temperature. To set it up simply follow the guide for monitoring temperature, but using the check_watchptHumid files. While the setup is the same as the temperature sensor, measuring humidity is a little different than temperature; humidity should ideally have a lower bound and a higher bound that you would like to monitor, with the humidity remaining in-between the two extremes. Because of this, there are two sets of thresholds you must pass to the plugin: the upper limits and the lower limits. The command format is:
perl check_watchptHumid_linux.pl -wu <upper warning level> -cu <upper critical level> -wl <lower warning level> -cl <lower critical level> [--port <port to use, default /dev/ttyUSB0>]
and a normal output might look similar to:
OK: Humidity is good at 41% | humidity=41;70;80;30;20;0;100
with a graph like:
Of course if you have any trouble setting up the plugin, please let me know and I’ll try to help.