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Entry type: FAQ Entry ID: 109766726, Entry date: 05/09/2019
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What should you watch out for with arrays and the data types DTL and LDT in the OPC UA server of a SIMATIC S7-1500?

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Please not the following information about arrays and the data types DTL/LDT in connection with the OPC UA server of a SIMATIC S7-1500.

Start indexes of arrays
When creating array tags in TIA Portal you should note that the OPC UA specification does not provide a definition of the start index. This means that the array always begins with the start index "0" via OPC UA regardless of the start index selected in TIA Portal.

Example
Definition in TIA Portal: Array [2..6] of Bool
Mapping in the OPC UA server: Array [0..4] of Bool 

Write protection for the data types DTL and LDT
You cannot access single elements of tags of the data types DTL and LDT via OPC UA. Therefore, as required, you extract the single elements in the user program and assign them their own tags.
 

Additional Keywords
OPC UA Server, DATE_AND_LTIME