OPC Factory Server (OFS) Tag Import Limitations
- Last UpdatedJul 18, 2023
- 3 minute read
Please be aware of the following limitations when importing tags from an OFS database.
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For each imported tag, the Plant SCADA tag name will be the same as the name of the tag defined on the OFS except "." characters will be replaced by "_" characters.
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Using OFS tag import to import tags from an OFS database may not succeed if Windows User Account Control (UAC) is enabled. UAC stops access to the external database. Either turn off UAC, or right click on the OFS and Unity Pro Windows shortcuts and select "Run as Administrator".
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To generate Alarm and Trend tags, a unique identifier can be set in the Custom and Comment field for Elementary Data Type (EDT) tags. For example, the string "VJA" is used to identify a tag that the user wants to use to generate a corresponding Digital Alarm Tag. Only the Comment field can be used for this feature on Derived Data Types (DDT) and Derived Function Block (DFB) tags.
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OFS built-in tags are not imported. They can be added in Plant SCADA manually.
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The length of the comment field in the Plant SCADA tag form is limited to 48 chaacters.
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Plant SCADA does not support DDT or DFB structure types. The OFS import will enumerate each element of this type of tag and import them as elementary tags.
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OFS tag import is only supported when the OFS links to the .STU and .XVM files.
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DFB components of type "ANY_ARRAY_xxxx" are not imported when the OFS links to a *.xvm file. When a data dictionary is used, the data dictionary ignores comment and custom fields and therefore taggen cannot generate alarm and trend tags. If there are DFB components of type "ANY_ARRAY_xxxx", the whole DFB is not imported.
The following table shows data types supported by the tag import and TagGen when the OFS links to *.stu or *.xvm file.
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OFS links to *.stu file |
OFS links to *.xvm file |
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|
Tag Import |
Tag Gen |
Tag Import |
Tag Gen |
||
|
Comment Field |
Custom Field |
Comment Field Only |
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|
Data Types |
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|
Elementary Data Types (EDT) |
|
|
|
|
|
|
BOOL |
Yes |
Yes |
Yes |
Yes |
Yes |
|
EBOOL |
Yes |
Yes |
Yes |
Yes |
Yes |
|
BYTE |
Yes |
Yes |
Yes |
Yes |
Yes |
|
INT |
Yes |
Yes |
Yes |
Yes |
Yes |
|
DINT |
Yes |
Yes |
Yes |
Yes |
Yes |
|
WORD |
Yes |
Yes |
Yes |
Yes |
Yes |
|
DWORD |
Yes |
Yes |
Yes |
Yes |
Yes |
|
UINT |
Yes |
Yes |
Yes |
Yes |
Yes |
|
UDINT |
Yes |
Yes |
Yes |
Yes |
Yes |
|
REAL |
Yes |
Yes |
Yes |
Yes |
Yes |
|
STRING |
Yes |
Yes |
Yes |
Yes |
Yes |
|
DATE |
Yes |
Yes |
Yes |
Yes |
Yes |
|
DT |
Yes |
Yes |
Yes |
Yes |
Yes |
|
TIME |
Yes |
Yes |
Yes |
Yes |
Yes |
|
TOD |
Yes |
Yes |
Yes |
Yes |
Yes |
|
|
|
|
|
|
|
|
Derived Data Types (DDT) |
|
|
|
|
|
|
EDT in DDT |
Yes |
Yes 2 |
No |
Yes |
Yes 3 |
|
Array in DDT |
Yes |
Yes 2 |
No |
Yes |
No |
|
|
|
|
|
|
|
|
Arrays |
|
|
|
|
|
|
Array of EDT 4 |
Yes |
Yes |
No |
Yes |
No |
|
Array of DDT 4 |
No |
No |
No |
Yes |
Yes 1 |
|
|
|
|
|
|
|
|
Function Block Types (FBT) |
|
|
|
|
|
|
Elementary Function Block (EFB) |
Yes |
Yes 2 |
No |
Yes |
Yes 3 |
|
Derived Function Block (DFB) |
Yes |
Yes 2 |
No |
Yes |
Yes 3 |
|
|
|
|
|
|
|
|
Synchronization |
|
|
|
|
|
|
Live Update |
No |
No |
No |
No |
No |
|
Automatic Refresh of tags |
No |
No |
No |
No |
No |
1. Only the BOOL type tags in the DDT can be used to generate Alarm and Trend tags when the OFS links to the *.xvm file.
2. When OFS links to the stu file, the comment string defined in the tag instance will be taken, the comment string defined in the DDT/DFB definition will be ignored.
3. When OFS links to the xvm file, the comment string defined in the DDT/DFB definition will be taken and the comment defined in the tag instance will be ignored.
4. Array with negative index is not supported.