Sorry for the delayed reply. I’ve been traveling the last couple days.
Yes, a SmartApp can do exactly that but it also relies on the DH to get the data from the device. In the water meter’s case, it’s neither a SmartApp or DH problem. The device handler actually sends every single reading to FortrezZ’s cloud to build the chart.
One option, as I mentioned above, is to request FortrezZ create an hourly chart that the DH just updates like it does today. I think that might take a while since there’s nothing really motivating them to do that.
The other option, which I think could be your best method would be to use one of a few existing SmartApps that log data elsewhere, like a Google spreadsheet. You can then go nuts with the data you collect. Here are a couple:
Here’s an example using Google and SmartTiles to display a chart:
And here’s another option for logging: