XML - Information
Use XML file as database with TF6420 Database Server
Execute XPath querries at a XML file wiht the TF6420 Database Server
You can find further information about XML-Schema here: http://www.w3.org/TR/xmlschema-0/
XML as Database
XSD-Schema for standard table structure
<?xml version="1.0" ?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:simpleType name="bigint">
<xsd:restriction base="xsd:long" />
</xsd:simpleType>
<xsd:simpleType name="datetime">
<xsd:restriction base="xsd:dateTime" />
</xsd:simpleType>
<xsd:simpleType name="ntext_80">
<xsd:restriction base="xsd:string">
<xsd:maxLength value="80" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="float">
<xsd:restriction base="xsd:double" />
</xsd:simpleType>
<xsd:complexType name="myTable_Double_Type">
<xsd:sequence>
<xsd:element minOccurs="0" maxOccurs="unbounded" name="row">
<xsd:complexType>
<xsd:attribute name="ID" type="bigint" />
<xsd:attribute name="Timestamp" type="datetime" />
<xsd:attribute name="Name" type=" ntext_80" />
<xsd:attribute name="Value" type="float" />
</xsd:complexType>
</xsd:element>
</xsd:sequence>
</xsd:complexType>
<xsd:element name="TestDB_XML">
<xsd:complexType>
<xsd:sequence minOccurs="1" maxOccurs="1">
<xsd:element name="myTable_Double" type="myTable_Double_Type" />
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>
XML file for standard table structure (Sample)
<?xml version="1.0" encoding="UTF-8"?>
<TestDB_XML xmlns:xs="http://www.w3.org/2001/XMLSchema-instance" xs:noNamespaceSchemaLocation="TestDB_XML.xsd">
<myTable_Double>
<row ID="1" Timestamp="2012-03-08T12:45:08" Name="TestValue1" Value="222.222" />
<row ID="2" Timestamp="2012-03-08T12:45:14" Name="TestValue1" Value="222.222" />
<row ID="3" Timestamp="2012-03-08T12:45:18" Name="TestValue1" Value="222.222" />
<row ID="4" Timestamp="2012-03-08T12:45:22" Name="TestValue1" Value="222.222" />
<row ID="5" Timestamp="2012-03-08T12:45:23" Name="TestValue1" Value="222.222" />
</myTable_Double>
</TestDB_XML>
Datatypes for XML tables
<xsd:simpleType name="bigint">
<xsd:restriction base="xsd:long" />
</xsd:simpleType>
<xsd:simpleType name="datetime">
<xsd:restriction base="xsd:dateTime" />
</xsd:simpleType>
<xsd:simpleType name="ntext_80"> <!-- Length can be set individually. -->
<xsd:restriction base="xsd:string">
<xsd:maxLength value="80" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="float">
<xsd:restriction base="xsd:double" />
</xsd:simpleType>
<xsd:simpleType name="binary_1"> <!-- Length can be set individually. -->
<xsd:restriction base="xsd:hexBinary">
<xsd:maxLength value="1" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="bit">
<xsd:restriction base="xsd:boolean" />
</xsd:simpleType>
<xsd:simpleType name="image_1"> <!-- Length can be set individually. -->
<xsd:restriction base="xsd:hexBinary">
<xsd:maxLength value="1" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="integer">
<xsd:restriction base="xsd:int" />
</xsd:simpleType>
<xsd:simpleType name="money">
<xsd:restriction base="xsd:double" />
</xsd:simpleType>
<xsd:simpleType name="nchar_50"> <!-- Length can be set individually.-->
<xsd:restriction base="xsd:string">
<xsd:maxLength value="50" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="nvarchar_50"> <!-- Length can be set individually.-->
<xsd:restriction base="xsd:string">
<xsd:maxLength value="50" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="real">
<xsd:restriction base="xsd:double" />
</xsd:simpleType>
<xsd:simpleType name="smallint">
<xsd:restriction base="xsd:short" />
</xsd:simpleType>
<xsd:simpleType name="tinyint">
<xsd:restriction base="xsd:byte" />
</xsd:simpleType>
<xsd:simpleType name="varbinary_1"> <!-- Length can be set individually.-->
<xsd:restriction base="xsd:hexBinary">
<xsd:maxLength value="1" />
</xsd:restriction>
</xsd:simpleType>
Datatype mapping XML => PLC
E_DBColumnTypes | XML | PLC Control |
|---|---|---|
eDBColumn_BigInt | xsd:long | T_LARGE_INTEGER (TcUtilities.lib) |
eDBColumn_Integer | xsd:int | DINT |
eDBColumn_SmallInt | xsd:short | INT |
eDBColumn_TinyInt | xsd:byte | BYTE |
eDBColumn_Bit | xsd:boolean | BOOL |
eDBColumn_Money | xsd:double | LREAL |
eDBColumn_Float | xsd:double | LREAL |
eDBColumn_Real | xsd:double | LREAL |
eDBColumn_DateTime | xsd:dateTime | DT |
eDBColumn_NText | xsd:string | STRING |
eDBColumn_NChar | xsd:string | STRING |
eDBColumn_Image | xsd:hexBinary | ARRAY OF BYTE |
eDBColumn_NVarChar | xsd:string | STRING |
eDBColumn_Binary | xsd:hexBinary | ARRAY OF BYTE |
eDBColumn_VarBinary | xsd:hexBinary | ARRAY OF BYTE |
Creating/Reading of data records into/from an XML file
For creating data records, it is possible to use standard SQL commands. The SQL INSERT commands will be interpreted of the TwinCAT3 Database Server and creates the specified XML-Nodes for the used XML file. The SQL SELECT commands will be converted to XPath queries which will be executed at the used XML file.
Samples for supported INSERT commands:
INSERT INTO myTable_Double (ID, Timestamp, Name, Value) VALUES(1, CURRENT_TIMESTAMP, 'TestValue1' , 1234.5678)
INSERT INTO myTable_Double (Timestamp, Name) VALUES(CURRENT_TIMESTAMP, 'TestValue1');
INSERT INTO myTable_Double VALUES(1, CURRENT_TIMESTAMP, 'TestValue1', 1234.5678);
INSERT INTO myTable_Double VALUES(1, '2010-01-06 12:13:14', 'TestValue1', 1234.5678);
Samples for supported SELECT commands:
SELECT ID, Timestamp, Name, Value FROM myTable_Double;
SELECT * FROM myTable_Double;
SELECT Timestamp, Name FROM myTable_Double
SELECT * FROM myTable_Double WHERE Name = 'TestValue1';
SELECT * FROM myTable_Double WHERE ID > 1;
Supported function blocks
FB_DBCreate
FB_DBCyclicRdWrt
FB_DBRead
FB_DBRecordArraySelect
FB_DBRecordDelete
FB_DBRecordInsert
FB_DBRecordInsert_EX
FB_DBRecordSelect
FB_DBRecordSelect_EX
FB_DBTableCreate
FB_DBWrite
XML standard XPath function
XPath Types
3 different modes are supported to read values of an XML file...
- XPath<ATTR>
- All attribute values of the selected XML tag will be returned to the PLC.
- If an XML-Schema is available the attribute values will be converted to the defined data types.
- If no XML-Schema is available all attribute values will be returned as T_MaxString
- XPath<TAG>
- The inner text of the XML tag will be returned to the PLC.
- If a XML-Schema is available the values will be converted to the defined data types.
- If no XML-Schema is available all values will be returned as T_MaxString
- XPath<SUBTAG>
- The inner text values of all XML subtags will be returned to the PLC.
- If an XML-Schema is available, the values will be converted to the defined data types.
- If no XML-Schema is available all values will be returned as T_MaxString
Samples
XML file:
<?xml version="1.0" encoding="utf-8" ?>
<TestXML>
<Node attr1="1" attr2="Node1">
<SubNode1>SubNodeWert1</SubNode1>
<SubNode2>200</SubNode2>
<SubNode3>SubNodeWert3</SubNode3>
<SubNode4>400.5</SubNode4>
<SubNode5>SubNodeWert5</SubNode5>
</Node>
<Node attr1="2" attr2="Node2">
<SubNode1>SubNodeWert1</SubNode1>
<SubNode2>200</SubNode2>
<SubNode3>SubNodeWert3</SubNode3>
<SubNode4>400.5</SubNode4>
<SubNode5>SubNodeWert5</SubNode5>
</Node>
</TestXML>
XML schema:
<? xml version="1.0" encoding="utf-8" ?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="TestXML">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="Node">
<xs:complexType>
<xs:sequence>
<xs:element name="SubNode1" type="xs:string" />
<xs:element name="SubNode2" type="xs:short" />
<xs:element name="SubNode3" type="xs:string" />
<xs:element name="SubNode4" type="xs:double" />
<xs:element name="SubNode5" type="xs:string" />
</xs:sequence>
<xs:attribute name ="attr1" type="xs:integer" use="required" />
<xs:attribute name ="attr2" type="xs:string" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
Sample for XPATH<ATTR>
XPath => XPATH<ATTR>#TestXML/Node[@attr1=2]
Returned structure if no XML schema is available.
TYPE ST_Record :
STRUCT
attr1 : attr1 : T_MaxString := ‘2’;
attr2 : T_MaxString := ‘Node2’;’;
END_STRUCT
END_TYPE
Returned structure if a XML schema is available.
TYPE ST_Record :
STRUCT
attr1 : DINT := 2;
attr2 : T_MaxString := ‘Node2’;
END_STRUCT
END_TYPE
Sample for XPATH<TAG>
XPath => XPATH<TAG>#TestXML/Node[@attr1=2]/SubNode2
Returned value if no XML schema is available: SubNode2 : T_MaxString := ‘200’;
Returned value if an XML schema is available: SubNode2 : INT := 200;
Sample for XPATH<SUBTAG>
XPath => XPATH<SUBTAG>#TestXML/Node[@attr1=2]
Returned structure if no XML schema is available.
TYPE ST_Record :
STRUCT
SubNode1 : T_MaxString := ‘SubNodeWert1’;
SubNode2 : T_MaxString := ‘200’;
SubNode3 : T_MaxString := ‘SubNodeWert3’;
SubNode4 : T_MaxString := ‘400.5’;
SubNode5 : T_MaxString := ‘SubNodeWert5’;
END_STRUCT
END_TYPE
Returned structure if a XML schema is available.
TYPEYPE ST_Record :
STRUCT
SubNode1 : T_MaxString := ‘SubNodeWert1’;
SubNode2 : INT := 200;
SubNode3 : T_MaxString := ‘SubNodeWert3’;
SubNode4 : LREAL := 400.5;
SubNode5 : T_MaxString := ‘SubNodeWert5’;
END_STRUCT
END_TYPE
Supported function blocks
FB_DBRecordSelect
FB_DBRecordSelect_EX
FB_DBRecordArraySelect