Formula Example: Creating a Phantom Site with Data From More Than One Site

So you have two pipes carrying storm water and they feed into a third pipe. You have instruments recording the flow in the third pipe and one of the feed pipes (we’ll say pipe 1). For the moment we will ignore gains and losses, as these are outside the arena of this demonstration.

Thus we will proceed on the assumption that the “sum” of the two pipes feeding the third is the resulting flow from the two source pipes. We have instruments watching the “third” pipe and one of the two “source” pipes (Pipe 1). Given all of the assumptions we’ve stated, the difference between the sum (flow in Pipe 3) and that coming in via Pipe 1, has to be flow of Pipe 2. This is trivial until someone actually wants a report printed, or even worse, a graph that includes the sum and both of the sources.

Rather than having to fire up a spreadsheet, import some numbers, and figure out how to plot it all - ou can quickly take advantage of FlowWorks Advanced Calculation Engine’s (FACE) ability to work with multiple Sites.

The process for making a phantom Channel is twofold:

  1. Start by creating a Calculated Channel. Once complete, you will need to proceed to step 2 (which is discussed in this topic). The image below shows Channel setup for this example:

  2. Configure a FACE formula calculation that commands the system to simply copy the data in from the original Channel (read below).

Important: These instructions are a continuation from the topic, "Creating a Calculated Channel". From step one, it is assumed that you are back at the Configure Sites Page, after having completed setup of a new Calculated Channel.

To configure FACE for the phantom Channel:

  1. Starting from the Configure Sites page, locate the Calculated Channel you just created. First find the Site that the Channel resides in, then choose the Channel.
  2. Click . This will direct you to the respective page, where summarizing information on the Calculated Channel is displayed.
  3. Click . This will take you to the page where you will configure the calculation. This page has three distinct sections - the following steps take you through each part, beginning from the top of the page.
  4. Provide a Calculation Name and Description (both are optional).
  5. For Calculation Type, select Formula.
  6. Ignore Start Date and End Date. We want this Channel to be filled with data points for the entire data stream we have available.
  7. Choose the Source Component. Source 1 is going to be the Channel we're calling "Pipe 3", and we will call it variable S since it is the SUM of the other two pipes. Click the drop-down arrow in the Site box and locate the Site that the Channel resides in. Use to add a second Source Component. for Source 2, locate the Channel we're calling "Pipe 1".
  8. Ignore Choose Lookup Table.
  9. Define the Equation. We are creating the calculation that will produce data points to fill the phantom flow Channel. If S = A + B, then B (the flow from the phantom Site "Pipe 2") will be equal to S – A. Thus S-A is our equation.
  10. Click .

You can now go to graphing and plot both the raw data channels and the Calculated channel. Graph for any time period you wish, and you will see that you ahve two sources and one sum.

This method demonstrates how you can use FACE to calculate new virtual data from two or more Channels. You can hand off this report or graph without the need to explain yet again how come you have measurements from Pipe 1 and Pipe 3 but not Pipe 2. We won’t tell them how you did it if you don’t.

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