The data key frame DataSetMessage data and related headers are shown in Figure 32.
Figure 32 – Data Key Frame DataSetMessage data
The encoding of the data key frame DataSetMessage structure is specified in Table 146.
If the key frame is a heartbeat DataSetMessage, only the header is encoded but the following structure shall not be encoded into the DataSetMessage. Generic Subscribers can detect heartbeat DataSetMessages if the DataSetMessage size equals the header size. If the DataSetMessage size is not part of the payload header, the DataSetMessage offset configuration is required on Subscriber side to identify a heartbeat DataSetMessage.
Table 146 – Data Key Frame DataSetMessage structure
|
Name |
Type |
Description |
|
FieldCount |
UInt16 |
Number of fields of the DataSet contained in the DataSetMessage. The FieldCount shall be omitted if RawData field encoding is set in the EncodingFlags defined in 7.2.4.5.4. |
|
DataSetFields |
BaseDataType [FieldCount] |
The field values of the DataSet. The field encoding depends on the DataSetFlags1.Field Encoding of the DataSetMessage Header defined in 7.2.4.5.4. The default encoding is Variant if bit 1 and 2 are not set. |
|
Padding |
Byte [*] |
Optional padding added if the encoded DataSetMessage is smaller than the ConfiguredSize. The DataSetMessage is padded with bytes with value zero. |