A common table may contain a master value for a certain property of several Data Terminals. AggreGate Server monitors changes in the common table and when these changes are detected it takes the "master" common table and copies it to several Devices.
Just like in the Master Properties of Group Members use case, the common table is created based on the value of a context variable, but here we're using a Data Terminal context variable. Same rules apply to the name and format of common table.
More information on this feature can be found here.
Real-World Example
For example, let's say our Devices have a "Checklist Table" setting, containing a list of things that should be checked by the Device operator after device startup. This Checklist Table should be same (or almost the same) for all Devices in the facility. Thus, we can create a Common Table that will contain "master" Checklist Table.
The creation process is quite simple. Note that this is a hypothetical example -- you might not have Devices with this exact setting. It's here just to give you a general idea of what the process looks like. This is how you would do it in AggreGate Client, had you had Devices with such a table:
1. Drag any Device node (
) in System Tree and drop it on the Global Common Data node (
).
2. Select Checklist Table from the drop down list:
3. A new Common Table will be created and shown in the System Tree:
4. Run the Edit Device Properties action for your Devices, go to the Device Settings Synchronization Options tab and change Synchronization Mode for Checklist Table to Use Server-Side Master Value. After that, select your new common table in the Master Value field:
5. Now, a new master Checklist Table will be written to all Devices. You could open the settings of any Device and see that its Checklist Table setting is not editable anymore. Instead, a button fills the row, with a label saying "Using common data table":
6. You can click this button to see what data was written from Common Table to the Device:
If it is necessary to exclude particular checklist items from some Devices, see the Record Permissions section to figure out how to do this.