There are many advantages to having RTUs (Remote Terminal Units) report data from distributed locations as data clients. Some of these benefits are described in the Client Advantages help topics. Acting as masters, these clients report datalog records based upon time or event to a central database that, acting as a server, accepts this data and acknowledges its receipt. These datalog records are time-stamped transactions that are transferred at a convenient time or in convenient batches using a simple interface.
Many SIXNET RTUs can report this data using only a single SIXNET Universal Driver message. The message fully identifies the data being reported including station identification, time stamping and record serial number to make the process of synchronizing the data into a database as easy as possible. If more data than will fit in a single message needs to be sent, the client station will send sequential messages (after receipt of an acknowledgement of the previous message). Similarly, many stations can report their data simultaneously, since the messages from multiple stations will stack in the incoming message buffer and be processed sequentially. Since each message fully stands alone and completely defines the references needed in each packet, large systems of asynchronous data reports can easily be accommodated.
At the server end, a runtime utility or a simple driver is needed to parse the received messages, store the data into the database in a manner appropriate for the application, and acknowledge the message. It is also possible to synchronize the clock in the remote station and assign a new reporting time by passing parameters back in the acknowledgement reply. SIXNET has two runtime utilities available:
The optional Datalogging feature set of the SIXNET I/O Tool Kit includes a Datalog Server that captures client datalog messages and writes the data to comma separated text files. This server will work well with many applications.
The Citect Datalog Server is optional Add-on software for the SIXNET I/O Tool Kit. This server captures client datalog messages and writes the data into the trend history files that are otherwise created and maintained by Citect HMI software. This server effectively provides a way for a Citect application to recover lost data as a result of communication loss or computer / Citect shutdown.
As an alternative to the two SIXNET servers above, you can Write a Driver to Accept a Datalog Client Message.
See Also: