Trend Requests

The Totalflow EIE provides various ways to request trends, depending on the Totalflow device model, the specified protocol, and the device's firmware version. DB2 protocol devices issue trend requests by time range. DB2 Enhanced protocol devices issue trend requests based on time range as well as sequence number range. Both protocols support the Get Latest From option.

The three data groups that define trend requests are "Trend List", "Trend Config", and "Trend - Device Specific". "Trend List" lists all of the trends created for a given device type. "Trend Config" enables you to configure "Trend - Device Specific" data groups and it generates configuration XML, which becomes available for viewing and editing. "Trend - Device Specific" collects and displays the retrieved trend data for a given trend.

For more information, see the following subsections below:

• Get Latest From Option
• Configuring a Trend
• To Create a Trend Data Group
• To View Trend Data
• Trend Retrieval Properties
• To View or Edit Trend Data Group XML

For more information, see Trend Tool.

Get Latest From Option

The Get Latest From feature is part of the Time Range option. The Get Latest From feature retrieves trend data from the most recently cached trend timestamp. After you use the Time Range or Sequence Number Range option to poll history for the first time, a timestamp is cached in the remote device. The cached timestamp marks when the most recent poll occurred and when to begin the next Get Latest From poll.

After the initial poll, every time you poll using the Get Latest From option a new most recent trend timestamp is cached in the remote device. The only way you can establish a cached trend timestamp after the initial trend poll is by enabling the Get Latest From option. For instance, if you disable Get Latest From and enter a Start Time value and retrieve data, the data corresponds to the Start Time entered but the timestamp as indicated in the field beside Get Latest From does not change.

Configuring a Trend

The Totalflow EIE device template files include a file that retrieves data from an ABB trend. This trend must be configured on the Totalflow remote device before it can be polled. Although CygNet provides alternate ways to trend field device data, trending at the remote device level in the Device Definition Service (DDS) is more reliable and precise since it does not depend on a communication device to constantly relay data.

To Create a Trend Data Group

1. In the remote device editor in the DDS, select the remote device for which you want to create a trend.
2. Click the Data Group page.
3. Double-click the Application Config data group. You must add and poll the Application Config data group before any trend- and register-based data groups will function.
4. Click Get from RTU. This populates the Application Config data group with all of the device applications you purchased rights to for the connected Totalflow device.
5. Close the Application Config dialog box and return to the Data Group page.
6. Click Add and select Trend List.
7. Double-click Trend List and click Get from RTU. The Enter Trend Folder dialog box appears.
8. Click OK if you want to retrieve trend-available devices from the \TREND\ folder. The \TREND\ folder is the default folder for trend-available devices. Note the file name of the device for which you want to create a trend data group.
9. Close the Trend List dialog box and return to the Data Group page.
10. Click Add and select Trend Config.
11. Double-click Trend Config and click Get from RTU. The Enter Trend Folder dialog box appears.
12. Append \TREND\ with the file name of the device for which you want to create a trend and click OK. All available data group elements for the selected device appear.
13. Go to the bottom of the dialog box, select Options, then select Create Data Group and click Yes. A new device-specific trend appears on your Data Group page.
14. Close the Trend Config dialog box.
15. Continue adding "Trend - Device Specific" data groups to suit your needs.

To View Trend Data

1. In the remote device editor in the DDS, select the remote device for which you want to create a trend.
2. Click the Data Group page.
3. Double-click the correct Trend - Device Specific data group and click View Data. A Trend - Device Specific dialog appears.
4. Click Get from RTU. A Trend Retrieval dialog box appears. The Trend Retrieval dialog box looks similar to the two following examples. The first example is a DB2 Trend Retrieval dialog box for an initial poll. The second example is a DB2 Enhanced Trend Retrieval dialog box with a selected Start Time that is not the latest cache time.

5. Set the Start Time and End Time, or Sequence Number Range, to suit your needs. For more information, see Trend Retrieval Properties below.
6. When you are done, click OK. The Trend - Device Specific data group table populates with data for the specified time or sequence parameters.

Trend Retrieval Properties

The following table lists and describes the properties found on the Trend Retrieval dialog box.

To View or Edit Trend Data Group XML

1. In the remote device editor in the DDS, select the remote device for which you want to create a trend.
2. Click the Data Group page.
3. Highlight the correct Trend - Device Specific and click Properties. A Data Group Properties dialog box appears.
4. Click Configure. The configured data group XML appears in an Edit Definition dialog box.
5. View and edit trend data group XML at will and at your own risk.
6. Click OK when you are finished editing XML.

Example

The following XML file is for a configured trend data group.