Civil Engineering Reference
In-Depth Information
receive into these Folders. The King will then assign Envelopes to Folders contain-
ing a Document of interest for the Kingdom. A Folder can be fixed, i.e. the Docu-
ment in the Folder is predefined or dynamic, i.e. the King can order the Mayor to
put a Document into a given Folder. The advantages of letting the King to decide
which Documents will be put into which Folders are that matching Documents in
different Cities will have a common identification throughout the Kingdom. The
disadvantage is that this requires some software and a City Founder may find it
too expensive and choose to have the Documents placed in fixed Folders to save
memory.
4.5.9
Folder Label
A Folder always has a label, the Folder Label. It contains the following information:
• Folder Number.
• Document List Number.
• Document Number.
• Transmit/Receive mark.
• The CAN Control Field according to the CAN specification.
• Remote Envelope(s).
• An Envelope can be set as “remote” according to the CAN specification by the
RTR bit. How RTR set to 1 is interpreted is dependent on the application cor-
responding to the Document in the Folder and has to be defined in the City docu-
mentation.
• Enable/disable the Folder.
• By disabling the Folder, any CAN communication by the application corre-
sponding to in this Folder is interrupted.
• Envelope(s) assigned to this Folder.
• Envelope(s) enable/disable.
• The use of an Envelope can be switched on or off with an enable/disable tag.
How a Page is identified in a Transmit Form List and put into a transmit Document
is depicted in Fig.
4.34
. Receiving Cities use the same Page Form in their corre-
sponding Receive Document.
As shown, a City Founder (module designer) does not have to care about how
his module will exchange information with other modules in a system. He has de-
fined what information his module needs and the timing constrictions. He has also
specified what kind of information the module can make available to other modules.
A Kingdom Founder can later on adapt the module to the needs of his system by
transmitting King's Pages at a start-up procedure and even dynamically tune it dur-
ing run time. Thus, the system designer can adapt and control the system using
the King in the Capital. Some diagnostics can only be made at the system level by
monitoring the traffic and getting internal information from modules. Any internal
