References
Placing a reference on an asset allows you to see a property from one asset when you look at another. For example, you can see if a pump is running when you look at a pressure transmitter.
You can create a reference to a single property, or to an entire asset.
A few uses of references are detailed below….
To Create A Summary
Occasionally, you'd like to create a single asset or an AR tag that gives you a brief overview of the important attributes of a system.
Creating an empty asset and filling it with references allows you to do this quite simply.
This is ideal when you are creating assets that provide summary information or that represent entire systems - you can pick and choose which pieces of information are most important.
When Property Flow Fails
There can be a number of reasons why property flow can fail - particularly when you're dealing with a flow-rate and you've got one or more dead-end forks in your system (forks that lead to assets that don't actually consume any of the flow).
In these cases, you can use references to make sure that users still see the upstream flow-rate.
When the Assets are Not Physically Related
If the relationship between two assets is logical, you can use references to display a property from the upstream asset on the downstream one, and vice-versa.
A common situation for this is when you have one component indirectly controlling another.
The temperature from sensor 'A' is fed to an analogue controller 'B', which is responsible for keeping the water temperature constant by adjusting valve 'C'.
Because the relationship between 'A' and 'C' is logical (they have a 'control' relationship, but no physical cable or piping directly between the two), property flow doesn't get a chance to work.
However, you can easily go to sensor 'A' and add a reference to the position property of valve C. And vice-versa, you could easily add a reference to A's temperature on C, and both of them on B.
This way, when you went to look at the controller, you'd see a property called 'Control Temperature' from A and a property called 'Valve Position' from C, without having to open each item separately.
When Displaying More Than One Of The Same Property
Some assets change the value of a measurement as it passes through. In ARDI, an asset can only be given one value for a given property.
For example, let's look at a heat exchanger. It takes in cold water and pumps out hot.
A heat-exchanger 'B' changes the temperature of the oil that passes through it. It sits between two temperature sensors. Sensor 'A' measures the incoming temperature, sensor 'C' measures the outgoing temperature.
But users who are going to be working on this unit would like to know the difference between these temperatures easily. This means showing both temperatures when someone looks at the exchanger itself - asset 'B'.
So we can add a reference called 'Outlet Temperature' on 'B' that reads the temperature from 'C'.
Unfortunately, the results are still slightly awkward - we have what is clearly an output temperature, but the inlet temperature is just called 'Temperature' (as it's come in via property flow).
Now there is a trick you can employ here. If you add a reference to a property that process flow would normally bring in anyway, it replaces it. This allows you to rename incoming properties from upstream.
So by adding a reference from 'B' to 'A' (even though the property in question already appears), you can name it 'Inlet Temperature'. This allows anyone viewing the heat exchanger to instantly know what both the inlet and outlet temperatures are, because they are clearly labeled.
Adding References
There is a page documenting how to add a reference to an asset.