An internal reference allows you to refer to any input, output, or parameter available in the current module. Internal references are best configured using the parameter browser available in all DeltaV expression dialogs. The browser brings up a graphical list of valid blocks, and parameters. By constructing a parameter path from the browser, you can avoid the potential of typographical errors and case sensitivity when referencing block parameters.
The fields for an internal reference parameter are described in the following table.
Internal Reference Parameter Fields
Name and Purpose |
Type |
Configurable |
Readable |
Writable |
| .CST (Connection Status) - Provides a means to tell if the reference has been resolved (that is, the value has been found and can be read) |
Integer | No | Yes -3 means 'external reference not resolved' -2 means 'parameter not configured' -1 means 'module not configured' 0 means 'good' 1 means 'not communicating' |
No |
| .AWST (Asynchronous Write Status) - Provides a means to tell if the last attempt to write the referenced parameter was successful |
Integer | No | Yes -4 means 'write rejected' -3 means 'external reference not resolved' -2 means 'parameter not configured' -1 means 'module not configured' 0 means 'success' 1 means 'not communicating' 2 means 'write pending' |
No |
| .ST - For more details, refer to the Function Block Status Values topic. |
Integer | No | Yes | No |
Note When using a reference field other than the .CV field, you will need to type the field name. For syntax rules regarding internal references, refer to the Internal References topic.
It is recommended that you verify internal references that are referencing either dynamic referencing parameters or external reference parameters. Follow the appropriate instructions on how to verify those parameters.