Siemens SIMATIC ET 200AL, System Manual

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OPC UA communication
9.1 What you need to know about OPC UA
Communication
Function Manual, 05/2021, A5E03735815-AJ
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9.1.7 Mapping of data types
SIMATIC and OPC UA data types
SIMATIC data types do not always correspond with OPC UA data types.
S7-1500 CPUs provide SIMATIC tags (with SIMATIC data types) to their own OPC UA server as
OPC UA data types. OPC UA clients can then access these tags with OPC UA data types via the
server interface.
A client can read the attribute "DataType" from such a tag and reconstruct the original data
type in SIMATIC.
Example
A tag has the SIMATIC data type "COUNTER". You read COUNTER → UInt16 in the table. You
now know that you do not need to convert; the COUNTER value is sent over the line as a
UInt16 data type.
The client detects from the attribute "DataType" that the tag is actually the SIMATIC data type
"COUNTER". With this knowledge, the client reconstructs the data type.
Table 9- 1 SIMATIC and OPC UA data types
SIMATIC data type OPC UA data type
BOOL Boolean
BYTE BYTE
→ Byte
WORD WORD
→ UInt16
DWORD DWORD
→ UInt32
LWORD LWORD
→ UInt64
SINT SByte
INT Int16
DINT Int32
LINT Int64
USINT Byte
UINT UInt16
UDINT UInt32
ULINT UInt64
REAL Float
LREAL Double
S5TIME S5TIME
→ UInt16
TIME TIME
→ Int32
LTIME LTIME
→ Int64