Modeling Ordered Message Definition

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Modeling Ordered Message Definition

Postby todd.yarrington@ge.com » Tue Nov 14, 2017 1:57 pm

Good Afternoon,

I am brand-new to SysML and would like to get some direction on how you would use SysML to define / model a message (header, payload, etc...) that has very strict ordering, sizing of fields, even internal to a field (endianness).

I will have probably 1000+ different messages to model, most of them are in table form today.

Please keep in mind that I'd like to keep an OSI model-like approach as well, as I don't want to redefine every layer for every message.

Below is an example message definition at the application layer that would be encapsulated by lower layers of protocol that I'll have to model as well (lower layers might be serial communications, Ethernet communications (TCP/IP), CAN, etc...).

Initially, I may only include the following types of information, but would like the ability to expand fields to include other types of information.

This can't be the first time this has been encountered, so I'd like an example if possible. In the quote below, if you copy / paste directly into excel, then do a "Text to Columns" w/ comma delimit, you'll see the table (roughly) to get an idea of how 1 application payload message might currently be defined. The forum isn't a great place for tables :)
Description,Type,Value,Range,Software Name,Notes
Packet,Octet,0001 0000,Fixed (32),time.packet,
Format,Octet,0100 0000,Fixed (64),time.format,
Version ,Octet,0000 0001,Fixed (1),time.version,
Year,Word,"YYYY YYYY
,,0XXX XXXX",1 to 32767,time.year,Refer to Note A
Month,Octet,0000 XXXX,1 to 12,time.month,Refer to Note A
Day,Octet,000X XXXX,1 to 31,time.day,Refer to Note A
Hour,Octet,000X XXXX,0 to 23,time.hour,Refer to Note A
Minute,Octet,000X XXXX,0 to 59,time.minute,Refer to Note A
Second,Octet,000X XXXX,0 to 59,time.second,Refer to Note A
Diagnostic,Discrete,HGFE DCBA,"A = 1 if valid; 0 otherwise
,,,B = 1 if UTC; 0 otherwise
,,,C = 1 if local; 0 otherwise
,,,D to H; spare (set to 0)",time.diagnostic

Thanks!
Todd
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Re: Modeling Ordered Message Definition

Postby donatas.mazeika@nomagic.com » Wed Nov 15, 2017 2:44 am

Hello,

Thank you for your interest.
Actually, SysML language is not out-of-the-box dedicated to OSI model-like approach. You could contact No Magic Professional Services (https://www.nomagic.com/services/professional-services) for information how SysML language can be tailored to this approach.

Also, you could take a look at our SysML documentation, where default SysML concepts related to data communication is provided:
- Sequence diagram: https://docs.nomagic.com/display/MD185/Sequence+diagram
- SysML Internal Block Diagram: https://docs.nomagic.com/display/SYSMLP ... ck+Diagram

Apart from diagrams, the model elements can be represented in tabular format:
- Generic table: https://docs.nomagic.com/display/MD185/Generic+table
- ICD table: https://docs.nomagic.com/display/SYSMLP ... +ICD+Table

If you will have more questions, feel free to ask.

Have a nice day,
Donatas Mazeika
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Re: Modeling Ordered Message Definition

Postby todd.yarrington@ge.com » Wed Nov 15, 2017 7:55 am

Hi Donatas,

Thanks for your response.

I took a look at your pages you've supplied and I had the understanding at the application level communications. While those are good references, I don't think it is exactly what I am looking for.

I did find this paper, although, I'm wondering how easy it is to import a table like mine to get this structure in MagicDraw.

http://www.omgsysml.org/A_modeling_pattern_for_layered_system_interfaces-INCOSE%20IS15_paper-sarrel-shames.pdf

Specifically, on sheet 10, figure 10 to start, then work my way down the stack. The paper isn't entirely clear on the process, just the end result. Maybe I just need experience in SysML to make the jump. I'd like to make as few jumps as possible to get the 1000+ messages into a model and still have it make sense & workable in the end.

Thanks,
Todd
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Re: Modeling Ordered Message Definition

Postby donatas.mazeika@nomagic.com » Wed Nov 15, 2017 9:52 am

In this case, you have a better understanding on how to map SysML elements with the data from your OSI model data:)

To fasten workflow of getting data from Excel or CSV file to MagicDraw, you could use Copy/Paste to tables capability (https://docs.nomagic.com/display/MD185/ ... astingdata). This functionality creates model elements with specific properties as is specified in a generic table. Also, there is Excel Importer plugin: https://docs.nomagic.com/display/EIP185 ... cel+import and in the new version of MagicDraw it'll be integrated Excel Sync capability too.

Best regards,
Donatas Mazeika
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