Trend and Graph Your Analog Values with These RTUs

Analog inputs are a great way to keep track of your sites. You can monitor precise voltages, fuel levels, temperatures, humidities and more. Analogs paint a much clearer picture than discrete contact closures.

The problem comes when you try to ask a historical question, like:

• What seasonal changes do we see in site temperature?
• How often do we REALLY refill our propane tanks?
• Did battery output voltage rapidly drop last night (failure), or was it a slow decline (drain)?

It's impossible to answer these questions accurately without gluing yourself to your screen 24/7. Unless, of course, your RTU supports analog trending and graphing.

Trending lets you see things hiding in plain sight

Trending is a massive help for multiple reasons - It makes the invisible become painfully obvious. With trending and analysis, you can see:

• Gradual reductions in HVAC performance over multiple days/weeks/months
• The root cause of strange heat spikes by comparing the log to another device's run events
• Seasonal weather effects on site temperature and humidity, allowing you to assess your thermal insulation

Some monitoring devices have analog trending capabilities built into their web interface. If you have this feature, then you're ahead of the game. The next step is utilizing them to understand your analogs and overall network health.

The NetGuardian 480 G4 web interface features analog graphing. It takes the data points from its internal log to do trending and analysis. You can also output the raw data to a CSV file.

Graphing makes your data easy to understand

Looking at raw analog trend data is a good first step, but it is still easy to miss something. Using graphs to visually represent analog data can make trends and potential problems stand out like a sore thumb.

Once you have a graph, some devices also allow you to export history as CSV. You can use Excel to create report, or import the data into SQL server for further analysis or raw queries with the tool of your choice.

URL-based CSV retrieval allows you to write a recurring cron job to extract a CSV on a regular basis (ex. daily), so you are always collecting and logging events and storing them in your company's central server (ex. SQL). GET parameters can be used with the history.csv or the eventlog.csv request to filter the returned data. When no GET parameters are supplied, all data will be returned in CSV format.

Export CSV files on demand or via cron job

Some devices from DPS Telecom, like the TempDefender G2, allow you to export data as a CSV.

This is an example from the TempDefender G2 user manual. By adding certain variables to the end of the IP address of your RTU device, you can request a customized CSV with the exact data you want. For more information, view the user manual.

CSV Export Example: http://192.168.1.145/history.csv?st=1397669439&et=1397671119

(In this example, we've requested all of the history events that occurred between two timestamps in UNIX format)

CSV export sample parameters:

It's also very easy for your IT team to write a cron job that will request, receive, and process a CSV at regular intervals. Once you've captured data in this way, you can analyze it using any of your favorite tools.

You need to start logging data now to make discoveries tomorrow

It's unfortunate, but insights you get from weeks and months of data logging don't happen unless you started logging data weeks and months ago. Don't wait any longer to start logging, graphing, and learning from your network alarm data.