Merit Tab and Quality Tab

Many tag types include a Merit tab or Quality tab on their tag properties folder. “Merit” and “Quality” are two names for what is essentially the same tab.  For input and status tag types, the screen will look like the following examples:

     

For output and control tag types, the Quality Based On field is replaced by a Security Bit setting.

Questionable Data

Questionable Data is a means of indicating that the data being reported by a tag might not be accurate. By default, the Questionable Data checkbox is selected for every new tag you create. This field is available for your convenience when commissioning a new system.  Before you have verified the accuracy of an I/O tag, the questionable data flag will be set and a question mark will appear on the tag’s drawing methods. 

After you have verified the accuracy of each tag’s data, you can un-check its questionable data marker, thereby keeping track of which tags you have verified and which you haven’t.

 

Quality Based On

VTS programmers can create their own custom tag types that are containers of other tags. For example, a pump station may have many pumps.  A city may have many pump stations. A county might have many cities. Container tags can be designed for each level, collecting data on pumps within that level.  For this type of application, the accuracy of the data depends on the status of all the pumps at all the stations, etc.  When one pump is out of communication, it is useful to know that the sum of the flow rates may therefore be inaccurate.

The Quality Based On field is not used by any of the standard VTS tag types. It is designed to be used with custom-coded container tags as just described.  For those with a solid understanding of VTS and a good knowledge of programming principles, the VTS Programmer’s Guide will help you to create your own container tags.

Security Bit

A Security Bit can be applied to any output or control tag. Using the drop-down list, you can select an existing application-specific privilege that will restrict output access for this tag. Once the bit is set, users will need to have that privilege granted to them before they can use this tag to send a signal to an I/O device.

Application privileges are added using the Administrative Settings security dialog. Please see: Add Application Privileges Using the Administrative Settings Dialog.