IFdtCommunication::ConnectRequest() method information

M&M FDT 1.2.1 Online Specification
IFdtCommunication::ConnectRequest() method information

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4.5.3.2 IFdtCommunication::ConnectRequest()

This method can be called in the states:

HRESULT ConnectRequest (
[in] IFdtCommunicationEvents* callBack,
[in] FdtUUIDString invokeId,
[in] FdtUUIDString protocolId,
[in] FdtXmlDocument fieldbusFrame,
[out, retval] VARIANT_BOOL* result
);

Description:

Establishes asynchronously a new communication link to a device specified by the fieldbus frame. ConnectRequest() establishes a routing to a device as a peer-to-peer connection.

Parameters:

callBack	Callback interface for the notification if the response is available
invokeId	Unique identifier for the request
protocolId	UUID of a fieldbusprotocol to be used. Identifies type of fieldbus specific schema
fieldbusFrame	Fieldbus-protocol-specific information how to connect. The structure is specified by a fieldbus specific schema e.g. like FDTHARTCommunicationSchema or FDTProfibusCommunicationSchema

Return Value:

result

TRUE Request sent FALSE Request refused

Behavior:

The method passes an XML document with communication parameters specified by a fieldbus specific schema. The fieldbus protocol to be used is identified by the parameter protocolId. Based on this information the method sends the request to the next communication component or to the connected device and returns without waiting for the established connection. The response will be provided by IFdtCommunicationEvents2::OnConnectResponse2(). The fieldbus frame contains additional fieldbus-protocol-specific information for the fieldbus master how to establish the connection. For example, information like repeat counts or preamble counts in case of HART sent by a DTM is a hint for the HART master. It is up to the environment to decide whether this information fits. Furthermore the fieldbus frame contains fieldbus-protocol-specific information how to address the device connected to a specific fieldbus. The systemTag provided in the connect request is the systemTag of the communication client. It can be used to retrieve the IDtm interface of communication client by calling IFdtTopology::GetDtmForSystemTag(). If the systemTag is empty (""), the communication client is not a DTM (may be the Frame Application or some other component).

Comments:

See also chapter FDT ‘Use Cases and Scenarios’.

Related dtmINSPECTOR hints:

Ralf Koban
created on 2006-12-05, last updated on 2007-01-30

Whenever a DTM accepts a ConnectRequest() it has to send an OnConnectResponse() (FDT 1.2) or OnConnectResponse2() (FDT 1.2.1).

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