Rockwell Automation 9301 Series RSView32 Users Guide - Manual (Page 124)

5–6

RSView32 User’s Guide
To create a derived tag:
1. In the Tag Name field, specify the name of the tag that will hold
the derived tag value. This tag can be analog, digital, or string and
can have device or memory as the data source. The tag name is
also the name of the derived tag file.
2. In the Description field, type a brief description of the derived tag’s
function. This description is for your information only—it does
not appear anywhere else.
3. In the Expression area, create the expression that will determine
the derived tag value.
For more information on expressions, see Chapter 14, Creating
expressions.
4. Click Accept.
5. Repeat Steps 1 through 4 to create more derived tags.
Use the Next button to move to a new record in the spreadsheet.
Editing derived tags
You can edit derived tags during development or runtime.
1. Open the derived tag file you want to edit.
2. Use the Prev and Next buttons to move among derived tags. Make
the required changes.
3. Click Accept to save the changes.
Limit the use of tags with device as their data source. If the
system is continuously writing the derived value to the device,
it can flood the communication channel with traffic. Also, if
writing occurs too often the buffer for the communication
channel can overflow and generate communication errors. IMPORTANT