That's the one. Any of the monitoring options will work for you, but the one you use should depend on how short you want the threshold to be.
The first script is used in a rule that allows all messages from all devices you want to monitor. It logs a time stamp, threshold, and nag timeout for each device every time it receives a message from each device.
The second script handles the alerts. It checks the last check-in time for each device compares that the current time. If you use the all-in-one option, it will also check to see if it has already alerted you within a set timeframe for the device and will wait if it has.
If you want your threshold to be measured in hours or days, then use a schedule for the second script. If you want your threshold to be measured in minutes (like 60 or less) and you are not already using keep-alives for something else, then that is probably the best option.
The last option is what I use because I measure some of my devices with 30 second thresholds. The all-in-one option requires you to uncomment the bottom of the script and throw away the second script, you won't need it. This option checks the thresholds for every device every time it receives a message from ANY device. Obviously you cant monitor a 30 second checkin if you only get a message every 2 minutes.
Let me know if you need any help getting it setup, there are comments in the script too.
