Calculate a sum or difference of water meters in Chart’nX

In a Chart’nX water dashboard, the Operations protocol calculates a meter’s value from other meters of the same group: a sum or a difference of known measurements. Fictitious example of a need: a measured primary volume minus a measured secondary volume. To add up all the secondaries in the primary, the Virtual (∑ secondaries) mode described in Add a water group is enough.

Intended for administrators and installers of a Chart’nX water dashboard.

Before you start

• The meters to combine already exist in the same group.
• Prepare the composition from the measurements of the installation: the measurements must cover the same periods and must not be counted several times.
• If the composition requires a chain of calculations that depend on one another, or a virtual primary that indirectly reuses its own result, have it validated by support before saving it.

Choose the calculated meter

1. Open the water dashboard with Configure, then find the group in Sub-meters.
2. In a secondary, or in the primary set to Real, give the result an explicit name and choose Operations in Protocol.

Compose the calculation

1. Click + Add operations. The Compose the calculation window lists, in its Meters section, the other meters of this group. The meter being composed cannot select itself.
2. Click each row to include. For each one, choose Sum to add it or Subtract to deduct it.
3. If the list is long, use Search for a meter…. Select all or Deselect all applies to the visible rows of the section. A selection hidden by the search stays kept: clear the search and reread everything before confirming.
4. Click Save in the window. The components and their signs appear in the card. Cancel in the window keeps the previous composition.
5. Reread the unit of the calculated meter and the selected components, then save the dashboard.

The Energy balance and Sub-meters shortcuts of the energy total window are not part of this flow: the water window only shows the Meters section.

Check the result

Open the dashboard over a known period and compare the result of the calculation with the expected measurements.

Troubleshooting

Message	Action
No meter is available for this operation.	Check that other meters have been created in the same group.
No meter matches this search.	Clear the search.
Unavailable meter	Reopen Add operations and identify the expected component. Remove a reference that has become unnecessary only if the calculation remains correct.

After deleting a meter, reread all the calculations concerned, their signs and their unit. To create another composition, add a new secondary and compose it explicitly.

If saving does not produce the expected components or if the values remain inconsistent after checking, see the water troubleshooting. If you cannot establish the correct composition, contact support@can-nx.com.