Details vs. the Bigger View…
Expenses such as battery life and communications charges can limit the volume of data you collect. But as a general rule, most users opt to collect from as many data points as their budget will permit. The more data points, the more visibility into the events being monitored.
To develop an understanding of the performance of their system and to report daily usages and volumes to regulatory bodies, engineers and operators often use collections of data over long periods of time. This can require the collected data to be input into a spreadsheet program, such as Excel, where formulae can be created to further analyze the data. This process can become cumbersome with new data arriving and having to repeat the Excel process.
By using the FlowWorks Advance Calculation Engine (FACE), the user can avoid exporting the data to Excel and take advantage of FlowWorks automatically processing newly arrived data as soon as it comes into the server.
The first decision you must make is which FACE function to use… sum or cumulative. The decision rests upon what you need as the output. If your only looking for the total of the data points within the selected time period, the sum function if your best option. However, if you also need the details leading up to that sum, use the cumulative function.
For example, let’s say that you have a rain gauge from which you are collecting data in 15-minute intervals and the data for an hour appears as follows:
If you run the sum function to total for the hour, you will get:
But if you require details that took you to that total, you can tell the cumulative function to total on an hour and you will see:
At the hour point, both functions reset the accumulator to zero and begin totaling the activity for the next reporting period (an hour in this example).
Continuing with this example, we’ll take our Rainfall data from the Demo Site “Demo Rainfall US” and create a cumulative function calculated channel that will reset daily.
First you will create a virtual (calculated) channel where you will “load” the calculated data.
You will do this by hovering over or clicking on the Management button in the FlowWorks menu and then clicking on the “FACE: Configure Sites” option in the menu that will appear.
Click on the drop down arrow in the “Choose Site” box to see the list of sites that you have access to. Then click on the site from which you will be obtaining your source data.
To create the new virtual channel to load the calculated date into, click on “Add New Channel”. Type a name in the “Channel Name” box… We’ll use Daily_Rainfall for this example and then you’ll click the drop down arrow in the channel units box and select inches.
Leave “Calculated” as the channel type because this data is all virtual and whenever we need it for reports or graphs, it is calculated from the source data channel.
Next click on the Create New Channel button…
After an OK, we are back at the configure sites window and our newly defined channel name should be displayed in the “Choose Calculated Channel” box. If it is not, click the drop down arrow in that box and select it.
Now to define the calculation. Click the “View Calculated Channel” button.
If this calculation had already been created, we would be taken to the calculation configuration screen, but since we have not yet created the calculation, we will need to click on the “Create Calculation” button.
Here is where we begin to define where to pull our source data and what to do with it. We will take the large window in three “sections.” First is a little documentation. Enter a name for this calculation – like “Compute Daily Rainfall” in the description box (you will want to enter enough of a description that when you come back to this in six months, you would have some idea of what it was that you were trying to accomplish).
In the next section of the screen we need to tell FlowWorks what type of calculation we want to create. We do this so that we can specify the pertinent configuration parameters. We’re going to create a cumulative calculation, so click on the drop down arrow in the “Type” box and then on the cumulative entry.
If we wanted to restrict the source data to be fed into our calculated channel for a particular date range, we could specify that at this time. However, we’d like to use any data recording during the sites span of existence for the rainfall channel from this site, so we will leave the start date and end date options blank.
The last section of the screen is where we are going to accomplish the “work” of configuring our calculation. First make sure that the source site and source channel appear in the appropriate box on the line labeled “Source Channel”. If not, click the drop down arrow in the box that needs adjusting and select the proper source.
Below the source channel site and channel name boxes find the “Interval Length” box. This is where we specify what our new “reset period” is (how often to “empty” our running total and start anew). We want to report the rainfall for a full day, so we click on the drop down arrow in the “Interval Length” box and click on 1 day.
You are now done proscribing the necessary configuration details for FlowWorks to create our new data stream, so you’ll click the “Save” button.
As you click OK and return to the view calculated channel screen, you can see that you now have a calculation displayed. [1440 is the number of minutes in 1 day – our new reset interval] and you can see that you are going to use the entire stream of available source data as our “Start Date” and “End Date” go from the beginning of the source data to the end of the source data.
Now we’ll skip right to graphing the output and selecting the source site. You will select the Rainfall Channel and your new Daily_Rainfall Calculated Channel and you’ll get:
The data that “fills” the virtual “Calcualted Daily_Rainfall” channel can be graphed (as above), reported, exported, and treated just as if it were data coming directly from your logger.