Introduction to the Direct Data Link Module
DirectDataLink is a connectivity and integration platform used to connect machine controllers to higher-level services and systems such as Nexeed Industrial Application System.
Main functions
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Provision of an exchange facility between the individual services, modules and the machine for information on functionalities
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Option of combining information on functionalities for complex processes
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Integration of different controllers through mapping of input and output formats and data pre-processing
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Value-added services such as data buffering for decoupling of communication and forwarding of incoming messages to a message bus
DirectDataLink System Architecture
The following figure shows the most important components of DirectDataLink.
+ DirectDataLink consists of three levels:
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The first level is formed by the communications modules, which serve as protocol and data format adaptors for machines from different manufacturers. Two communications modules are provided for OpCon XML and for the Production Performance Management Protocol (PPMP). OpCon XML messages are transmitted via TCP, while PPMP messages are sent via HTTP(S). For example, a data source for PPMP messages can be the IoT Gateway, while the OpCon XML messages can be sent from PLCs and stations from multiple providers.
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The second level consists of the internal services for reading the configuration, buffering, variable mapping, and conditional execution of processing steps.
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The third level consists of the processing modules that convert the data into the format expected by the target services. The target services can be in the cloud as well as on premise. With the PPMP Access processing module, the data can be sent via HTTP(S) to performance monitoring, line management, etc. On the other hand, data can also be sent to order management via WCF.
The two communications modules (XML and PPMP) and the two processing modules (PPMP Access and for order management) are described in the following chapters.
XML Communications Module
The OpCon.DDL.Communication.CommOpConXML.dll communications module enables data exchange between the PLC and the OpCon DirectDataLink ExecutionEngine Service. Data is transferred in a defined XML format via TCP/IP (Windows Sockets).
Telegrams (events) which do not correspond to the specified schema are rejected, and an error is generated and logged internally. See document OpConXML.pdf.