Figure 8 shows the SercosParameterType. The SercosParameterType is a subtype of BaseDataVariableType (defined in OPC UA specification OPC 10000-5) and represents Sercos Parameters.

image012.png

Figure 8 – Sercos ParameterType

All the SercosParameterType instances of each device are referenced as component from the ParameterSet Object (BaseObjectType) (defined in OPC UA specification for devices).

Every Sercos Parameter consists of elements. Elements are used to supply all information about the Sercos Parameter. The value of the parameter is transformed according to the DataType transformation rules (defined in 4.3.3). The attribute element contains e.g. read and write access rights and is mapped to the OPC UA attributes (for more information see Sercos Generic Device Profile specification).

SercosParameterType is formally defined in Table 9.

Table 9 – SercosParameterType Definition

Attribute

Value

BrowseName

SercosParameterType

IsAbstract

False

ValueRank

-2 (-2 = any)

DataType

BaseDataType

References

NodeClass

BrowseName

DataType

TypeDefinition

ModellingRule

Subtype of the BaseDataVariableType defined in OPC UA specification OPC 10000-5.

HasProperty

Variable

Attribute

UInt32

PropertyType

Mandatory

HasProperty

Variable

DisplayValue

String

PropertyType

Mandatory

HasProperty

Variable

DisplayMaxValue

String

PropertyType

Optional

HasProperty

Variable

DisplayMinValue

String

PropertyType

Optional

HasProperty

Variable

Exponent

SByte

PropertyType

Optional

HasProperty

Variable

MaxValue

BaseDataType

PropertyType

Optional

HasProperty

Variable

MinValue

BaseDataType

PropertyType

Optional

HasProperty

Variable

ProcedureCommand

Boolean

PropertyType

Optional

Attribute (OPC UA Property) represents the Sercos Parameter element Attribute, which contains bit-coded data. Parts of this element are mapped to individual elements as following:

DisplayValue represents the converted Sercos Parameter value as an ASCII String. Decimal seperator is formatted with respect to the given “locale” (“locale” is a set of parameters that defines the user's language, country and any special variant preferences).

DisplayMaxValue and DisplayMinValue converts the value of MaxValue and MinValue to String respectively.

Exponent is the optional scaling element of each parameters value (operational data) which applies on DisplayValue. For instance, Exponent of 1E-4 is -4 for both signed and unsigned decimal data types.

MaxValue is the largest numerical value for the parameter, which can be processed by the Sercos device. When, in a write request for the parameter, the MaxValue is exceeded, the value of the parameter is not changed and related OPC UA StatusCode will be returned. The source of MaxValue is the Sercos element Maximum Value of the parameter.

MinValue is the smallest numerical value for the parameter, which can be processed by the Sercos device. When, in a write request for the parameter, the MinValue is exceeded, the value of the parameter is not changed and related OPC UA StatusCode will be returned. The source of MinValue is the Sercos element Minimum Value of the parameter.

ProcedureCommand Variable shows whether the parameter is a Sercos procedure command (=true) or not (= false).

The Sercos Parameter Names are corresponding to the IDN notation, e.g. “S-0-1301-0.1”.

Sercos Procedure Commands are accessible as OPC UA Methods. These shall be referenced by the “MethodSet” object. Figure 9 shows an example model with Sercos Procedure Command Methods.

image013.png

Figure 9 – Example model with Sercos Procedure Command Methods

The Method BrowseName and DisplayName contain the IDN as String, e.g. “P-0-0014”. The invocation of the Sercos Procedure Command Method causes the execution within the Sercos device.