09-08-2008 04:50 PM - last edited on 09-15-2008 12:13 PM by Support
This thread is intended to foster discussion regarding the LabVIEW DSC Tag API. Please post any comments or questions about the API here.
The Tag API provides an additional method for accessing live and historical data and alarms using the Datalogging and Supervisory Control Module. The Tag API is written completely in LabVIEW on top of current LabVIEW DSC APIs to help users write better DSC applications. This high-level dynamic shared variable API allows users to write DSC applications using tag names instead of shared variable URLs. Tags are defined as a datasource that includes live, alarming, and historical data. A tag is different than a shared variable in that a shared variable only references live data. The Tag API utilizes the shared variable, Citadel database, and alarm server to provide all information about a tag.
LabVIEW 8.6LabVIEW DSC 8.6
10-14-2008 02:28 PM
The DSC Tag API is built on LabVIEW Classes so you shouldn't need anything special other than to build it into an EXE to use part of the API for distribution. Thanks!
10-23-2008 02:58 PM - edited 10-23-2008 02:59 PM
There isn't a lot of documentation currently for the API, but I can attach a simple example and give some compelling use cases. Attached below is a simple example of how you would use the API to read a value from a variable.
The reason why you may want to use this approach is that the value, the historical data, and the alarm data is all part of what we refer to as the tag. Instead of needing to know addresses for historical reads, we take care of that using the refnum. All you would need to do is open a refnum for a specific library and access each variable by name.
The HVAC example attached below shows how to implement a fairly complicated HMI using the event structure, subpanels, and the DSC Tag API.