Mapping UDCs
To bring a data group element into the system from a remote device, a UDC must be "mapped" to the element. For example, if analog input 01 represents static pressure, you would map the UDC for static pressure to that analog data group element (AI01 = PSTATIC). A point can then be created based on that mapping, with the UDC being a property of the point.
UDCs are mapped to data group elements on a facility basis. You can use the same UDC for any number of facilities. But within a data group (a collection of data group elements), the facility-UDC combination must be unique. If the same data group element is included in separate data groups, you can use the same facility-UDC combination in both data groups.
Example
You can assign the UDC "PDIFF" to all elements in a data group that represent differential pressure if they are in different facilities.
| Data Group Element | Represents | UDC | Facility |
|---|---|---|---|
| AI03 | Diff Pressure | PDIFF | JONES_METER1 |
| AI04 | Diff Pressure | PDIFF | JONES_METER2 |
| AI05 | Diff Pressure | PDIFF | JONES_METER3 |
Example
If multiple data group elements in a data group represent the same type of item, such as two analog inputs that represent the levels of two tanks, you must ordinalize the UDC because within a data group the facility-UDC pairing must be unique.
| Data Group Element | Represents | UDC | Facility |
|---|---|---|---|
| AI08 | Tank Level | LTANK1 | JONES_NORTH |
| AI09 | Tank Level | LTANK2 | JONES_NORTH |
To Map UDCs
Note: If you add UDC mapping to a template, the change does not apply to already existing devices. Instead, manually edit mappings in an affected device first, using options available on the Uniform Data Code Assignment dialog box in the DDS. Then use the CygNet DDS Data Group Copy Utility to apply the updated mappings in bulk to other existing devices.
- In CygNet Explorer, open your Device Definition Service (DDS), click the Remote Devices page, and double-click the device you want to alter.
- Click the Data Group page, highlight the data group type you want to alter, and click Map UDCs.
Note: If a required data group is not present, click Add and select the data group from the list of available groups, then proceed.
- Highlight a data group element and click Map.
- Highlight the appropriate UDC and click Assign UDC.
- To delete a UDC assignment, highlight the incorrectly mapped data group element in the Uniform Data Code Assignment dialog box and click Remove Mapping.
- When you are finished mapping UDCs on the Uniform Data Code Assignment dialog box, click OK.
- At the data group Properties dialog box, click Apply.
Non Device-Related Points and UDCs
For points that are not device-related, UDCs can still be used for standard data identification. An example of a non-device related point is a point that represents an item from an OPC server. If that item is also static pressure, the UDC of the point would be PSTATIC. The difference in this case is that the UDC is not "mapped" to a data group element in a device. It is just a property of the point.
