Sankey+

Overview

When to use it

Use Sankey+ when you need to:

• Show how a total is split between consumers, such as energy, water, or material.
• Compare the size of several flows in one picture.
• Combine live process values with fixed reference flows that have no data source.
• Find where a balance gains or loses something, because a node that takes in more than it passes on stands out.

Choose Pie Chart+ when you only need the share of each part in one total, with no stages between source and destination.

Before you begin

• Prepare one numeric PI Point or AF attribute for each live flow, all in the same unit. The band width is the plain number. Sankey+ does not convert units.
• Decide the nodes of the diagram and, for every flow, the node it starts at and the node it ends at.
• Plan a network without loops. A flow that would close a loop is not drawn.

Add and set up the symbol

1. Select Sankey+ in the PI Vision symbol gallery.
2. Drag the numeric data sources onto the display together. Each data source becomes one flow.
3. Right-click the symbol and select Configure Sankey.
4. In the Nodes section, select + once for each node of the diagram. Enter its Name.
5. In the Flow Options section, select the first flow. Set Start and End to its nodes.
6. Repeat step 5 for every flow, then click an empty part of the display.

The symbol draws one band per flow, and each node is as tall as the flows through it.

Common tasks

Connect a data source to its nodes

Use this when a flow is missing from the diagram or runs between the wrong nodes.

1. Right-click the symbol and select Configure Sankey.
2. In the Flow Options section, select the data source in the list (1).
3. Set Start (2) to the node the flow leaves.
4. Set End (3) to the node the flow enters.
5. Optionally set Label to a name for the flow, and Value Type to Average, Maximum, or another statistic over the display time range instead of the current value.

The band appears between the two nodes with its width following the value. A flow whose Start or End is empty is not drawn.

Add a fixed flow

Use this for a flow that has no data source, such as a contract value or a figure from a meter that is not in PI.

1. In the configuration pane, open the Static Flows section.
2. Select + (1) to add a flow.
3. Enter the Name (2) and the Value (3).
4. In Units (4), select the unit to print after the value.
5. Set Start (5) and End (6) to the nodes the flow connects.
6. Set Color, and set Label to ON to show the flow label.

The fixed flow joins the live flows. In the first image of this article, the Supplier delivery and the two bands that leave Tank farm are fixed flows. A new fixed flow has no color and no label until you set them. The value is shown as you typed it and does not follow the number format.

Color the flows

Use this when the bands should read as a family, or when a flow must keep one fixed color.

1. In the configuration pane, open the Trend Options section and then the Flows group.
2. Set Color (1) to Node to color the bands from the nodes, or to Flow to use the color of each data source.
3. For Node, set Type (2) to Source, Target, or Gradient.
4. Drag Opacity (3) to make the bands more or less transparent.
5. For Flow, select a data source in Flow Options and set Color to Custom, or select the multi-state button next to it to color the flow by value.

With Gradient, each band fades from the color of its start node to the color of its end node. Fixed flows keep the color you gave them.

Show names, values, and direction on the flows

Use this when readers need the numbers on the diagram or must know which way a flow runs.

1. In the configuration pane, open the Data Labels group.
2. Under Nodes, switch Name (1) and Value on or off. Select the unit in Units (2).
3. Under Flows, set Direction (3) to ON to draw an arrow on each flow.
4. Set Name (4) to ON to show the flow name above its value.
5. Optionally set the node label Position to Top, so that node labels stay clear of the flow labels.

Each flow now shows an arrow, its name, and its value with the unit of its data source. To hide the label of a single flow, select it in Flow Options or Static Flows and set its Label to OFF.

Tidy the layout

Use this when nodes crowd each other, or when the diagram should line up toward its targets.

1. In the configuration pane, open the Nodes group.
2. Keep Position on Auto and set Alignment (1) to Left, Right, or Auto.
3. Drag Width (2) to change the thickness of every node.
4. Drag Distance (3) to change the space between nodes in a column.

With Right, each node moves toward the column of the node it feeds, so Terminal 1 and Supplier sit next to Tank farm and not at the far left. To place nodes by hand, set Position to Custom, select a node in the Nodes section, and use the arrow buttons under Node Position to move it by column (X) and row (Y).

Use the symbol

• Hover a flow or node to see its tooltip.
• Click a live flow to open a Quick Trend of its data source over the display time range. A fixed flow has no data source and opens nothing.
• Fullscreen shows the same diagram in a larger window without loading data again.
• Download exports the diagram as PNG, SVG, or PDF, or the flows as CSV, JSON, or XLSX. A data export has one row per flow, live flows first, with Source, Target, Flow, Value, and Units. If your administrator disables data exports, only the image formats are offered.
• Toolbar: by default it appears when the pointer enters the symbol. Under Toolbar, set Reveal to Always to keep it visible.
• Balance: when a node takes in more than it passes on, or the other way around, it is as tall as the larger side and the smaller side leaves a gap. A balance that does not close shows up as a node taller than its outgoing bands.
• No data: a flow whose data source has no good value is drawn with width 0 and shows its state, such as No Data, in its label.
• The symbol only displays data. It does not write to the PI System or change other symbols.

Configure the symbol

Right-click the symbol and select Configure Sankey. The pane has these sections: Trend Options with six groups, then Nodes, Flow Options, Static Flows, and Numbers.

Title

Style

Flows

Nodes

Data Labels

Toolbar

Nodes section

Flow Options section

Static Flows section

Numbers

Troubleshooting and limitations

Limitation: Sankey+ does not support loops. A flow that would close one is left out.

Limitation: The band width is the plain number of the value. Sankey+ does not convert units and does not check that flows balance.