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A DataSet field consists of a value and related metadata. In most cases the value comes with status and timestamp information.
This DataType defines flags to include DataSet field related information like status and timestamp in addition to the value in the DataSetMessage.
The DataSetFieldContentMask is formally defined in Table 14.
The handling of bad status for different field representations is defined in Figure 21 and Table 16.
Table 14 – DataSetFieldContentMask Values
|
Value |
Bit No. |
Description |
|
DataSet fields can be represented as RawData, Variant or DataValue as described in 5.3.2. If none of the flags are set, the fields are represented as Variant. If the RawData flag is set, the fields are represented as RawData and all other bits are ignored. If one of the bits 0 to 4 is set, the fields are represented as DataValue. |
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|
StatusCode |
0 |
The DataValue structure field StatusCode is included in the DataSetMessages. If this flag is set, the fields are represented as DataValue. |
|
SourceTimestamp |
1 |
The DataValue structure field SourceTimestamp is included in the DataSetMessages. If this flag is set, the fields are represented as DataValue. |
|
ServerTimestamp |
2 |
The DataValue structure field ServerTimestamp is included in the DataSetMessages. If this flag is set, the fields are represented as DataValue. |
|
SourcePicoSeconds |
3 |
The DataValue structure field SourcePicoSeconds is included in the DataSetMessages. If this flag is set, the fields are represented as DataValue. This flag is ignored if the SourceTimestamp flag is not set. |
|
ServerPicoSeconds |
4 |
The DataValue structure field ServerPicoSeconds is included in the DataSetMessages. If this flag is set, the fields are represented as DataValue. This flag is ignored if the ServerTimestamp flag is not set. |
|
RawData |
5 |
If this flag is set, the values of the DataSet are encoded as Structure and all other field related flags shall be ignored. The RawData representation is handled like a Structure DataType where the DataSet fields are handled like Structure fields and fields with Structure DataType are handled like nested structures. All restrictions for the encoding of Structure DataTypes also apply to the RawData Field Encoding. Fields shall not have an abstract DataType or shall have a fixed ValueRank. Fields shall have dimensions defined if the DataType is String or ByteString or if it is an array. This includes Structure fields with such fields. The flag shall be ignored and the fields shall be represented as Variant if the fields do not fulfil these requirements. |
The DataSetFieldContentMask representation in the AddressSpace is defined in Table 15.
Table 15 – DataSetFieldContentMask Definition
|
Attributes |
Value |
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|
BrowseName |
DataSetFieldContentMask |
||
|
IsAbstract |
False |
||
|
References |
NodeClass |
BrowseName |
DataType |
|
Subtype of UInt32 defined in OPC 10000-5. |
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|
HasProperty |
Variable |
OptionSetValues |
LocalizedText [ ] |
The DataSetFieldContentMask defines different options that influence the information flow from Publisher to Subscriber in the case of a Bad Value Status or other error situations. Figure 21 depicts the parameters and the information flow from DataSet field to DataSetMessage creation on Publisher side and the decoded DataSet field on the Subscriber side. The DataSetFieldContentMask controls the representation of the DataSet fields in a DataSetMessage.
Figure 21 – PubSub Information Flow dependency to field representation
The representation of the DataSet fields in a DataSetMessage on the Publisher side and the decoding back to the DataSet fields on the Subscriber side is defined in Table 16. The representation on the Publisher side depends on the field representation defined in the DataSetFieldContentMask.
Table 16 – DataSetMessage field representation options
|
DataSet Publisher |
Field |
DataSetMessage |
DataSet Subscriber |
|||
|
Value |
Status(4) |
|
Value |
Status(4) |
Value |
Status(4) |
|
Value 1 |
Good_* |
Variant |
Value 1 |
N/A (1) |
Value 1 |
N/A (1) |
|
Value 1 |
Uncertain_* |
|
Value 1 |
|
Value 1 |
|
|
Null |
Bad_* |
|
Bad_* (1) |
|
Null |
Bad_* |
|
Value 1 |
Good_* |
DataValue |
Value 1 |
Good_* |
Value 1 |
Good_* |
|
Value 1 |
Uncertain_* |
|
Value 1 |
Uncertain_* |
Value 1 |
Uncertain_* |
|
Null |
Bad_* |
|
Null |
Bad_* |
Null |
Bad_* |
|
Value 1 |
Good_* |
RawData |
Value 1 |
N/A |
Value 1 |
N/A |
|
Value 1 |
Uncertain_* |
|
Value 1(2) |
|
Value 1 |
|
|
Null |
Bad_* |
|
DefaultValue(3) |
|
DefaultValue |
|
|
Note 1: A bad status is transferred instead of a value. An uncertain status is not transferred for a field. If the status field is included in the DataSetMessage header, the status is set to uncertain if one of the fields has an uncertain status. Note 2: If the worst status for one or more fields is uncertain, the DataSetMessage status shall be set to Uncertain. Note 3: If the worst status for one or more fields is bad, the DataSetMessage status shall be set to Bad. Note 4: If no specific StatusCode is used, the grouping into severity Good, Uncertain or Bad is used. In this case, the resulting Status matches the input Status. |
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