Monitoring Data From Client Systems Using Tags

[allen_h]

This document is part of the SystemLink Portal.

Monitoring Data From Client Systems Using Tags

Use the following instructions to do the following:

1. Write data to tags from an application running on your client systems.
2. Monitor the value of tags from the SystemLink web UI.
3. Set an alarm and email notification based on the value of a tag.

Tags are meant for data communication of scalar values (numeric, string, Boolean, timestamp) at slower rates of 1 Hz or less.

Write to Tags from an Application Running on a Client System

Use the SystemLink Tag and Configuration APIs to do the following:

1. Open a connection with a SystemLink Server.
2. Open a reference to an existing/new Tag.
   
   Note If you are creating a new tag and you want that tag to show up in the "Alarms and Tags" tab on the Client's single system page, then make sure you set the Tag name to <minion ID>.<my tag name>
   (e.g. MyPC-SN-9W08TK2-MAC-08-00-27-05-24-68.mytemperaturetag).
   
   To get the minion ID, the LabVIEW SystemLink API has a Get Minion ID function.
   
   
3. Write and/or read values to the Tag.
4. Close the reference to the tag when finished with all reads/writes.
5. Close the connection to the SystemLink Server.

Refer to the Transferring Data Using Tags topic for more information about the above steps, along with an example.

SystemLink automatically creates and monitors the following tags out-of-the-box for every Client system (e.g. desktop PC, cRIO, PXI controller, etc).

• CPU usage (% usage per CPU and overall, # of CPUs)
• Memory usage (% usage, free, total, used)
• Disk usage (% usage, free, total, used)

As reference, here are links to the SystemLink APIs in various languages.  Refer to the "Tag" functions in these APIs.

• LabVIEW G API :: Examples located in the NI Example Finder under Toolkits > SystemLink > Tag
  Note: To install the LabVIEW G API on a development computer, install the LabVIEW SystemLink Toolkit (download link).
• LabVIEW NXG G API 
• HTTP API
• Python API
• .NET API

Example LabVIEW API

Monitor Tag Data from the SystemLink Web UI

(Out-of-the-Box Views)

Tag Viewer

To view all tags from all Client systems, follow these steps:

1. From the SystemLink web UI, click the Tag Viewer web application.
2. Use this page to view a table of all tags from all Client systems.
3. Use the search bar and Filter button to filter the table to show only the relevant tags.  The search bar accepts the wildcard character (*).

For details on the Tag Viewer, refer to the Verifying Your Tag Data in Tag Viewer topic.

Single System page > Alarms & Tags tab

To view all tags for only a single specific Client system, follow these steps:

1. From the SystemLink web UI, navigate to one of your managed Client systems.
2. Go to this system's Alarms and Tags tab to view only the tags associated with this single system.
3. Use the search bar to filter the tags even more, if needed.

Tag Historian

To view the historical trend of values for a Tag, follow these steps.

1. From the Tag Viewer table or Single System's Alarms & Tags tag table, double-click the Tag of interest.
2. View the historical values of the Tag on a graph (if numeric values) or table (if string values).  Hover your mouse cursor over the various points on the graph (if numeric) to view the values of individual points.
3. (Optional) By default, SystemLink will retain Tag values for the last 30 days.  However, you can use the Retention item on this page to the Retention logic to one of the following:
   • Duration - Retain for a different number # of days
   • Count - Retain only the past n count of values
   • None - Do not retain any historical data
   • Permanent - Retain all historical data
4. (Optional) You can also use this page to manually set keywords and custom properties for your tag.  This allows you to add metadata and make it easier to filter/search your tags.

For details, refer to the Verifying Your Tag Data in Tag Viewer topic.

Monitor Tag Data from the SystemLink Web UI

(Custom Dashboard)

One way you can monitor tag values from the SystemLink web UI is by creating a custom dashboard using the Dashboard Builder.

For instructions, refer to the Visualizing Data on a Dashboard topic.

Note If you want to create a custom dashboard for a single system and you want to reuse the same dashboard for multiple systems, you can add a System Filter which will show a dropdown menu that allows the end-user to select which system (and corresponding tags) to apply the dashboard to.  To add a System Filter, click the Gear icon on the dashboard and turn on the System Filter toggle button.

Example Dashboard (with System Filter)

Configure Alarms/Notifications Based on a Tag

To configure an alarm and email notification that is triggered by tag value conditions, refer to the Monitoring System Health with Alarms topic.