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kalabdel January 13th, 2021 08:52 PM

System design and modeling, what do you use?
 
Hello everyone,


I've tried quite a few methods over the years starting with flow charts and finite state machine diagrams and then often a combination of the two. Last year a spent sometime on State-charts and it worked well for me though the IDE I was using, "Yakindu", and like the modeling system but not quite confident with Yakindu IDE.

I am now more inclined to invest time getting good at SysML


I have two objectives, one is to aid in the process of system development as it relates to PLC programming and the other is for documentation and customer presentation.



What do you use, works well for you and is accepted by your customers?


Thanks
Kal

kalabdel January 14th, 2021 01:26 AM

Hello everyone,
I've tried quite a few methods over the years starting with flow charts and finite state machine diagrams and then often a combination of the two. Last year I spent sometime on State-charts and it worked well for me and like the modeling system but not quite confident with Yakindu IDE which I was using at that time.
I am now more inclined to invest time getting good at SysML

I have two objectives, one is to aid in the process of system development as it relates to PLC programming and the other is for documentation and customer presentation.

What do you use, works well for you and is accepted by your customers?

Thanks
Kal




Edit(sort of) to clean it up a bit.

JeremyM January 14th, 2021 10:52 AM

The best flow chart is the one that ends in its own deletion. The only fathomable reason these cockroaches persist is that their nesting environment (the university curated by those that don’t participate in the real world) continues to output graduates that bring them to bear... initially.

I despise flow charts. Nothing else than one of these abominations breeds poor documentation, indecision, confusion, poor programming, hard-coded programming, hack jobs, fudge jobs, software bugs, deep magic, and general BS. Well, perhaps a flow chart spanning more than one page.

State machines are predictable, finite, easy to document, and far easier to implement. They’re also infinitely scalable via nested machines (within memory limits of course). PackML / IS88 is a model you can consider (and should at least study) if you’re trying to generalize your approach. The state model is unidirectional but unused states can be configured as such. A shortcoming is the potential for idle code in the finished product, but IMO this is more than outweighed by gains. Machine-to-machine interfaces are also far more meaningful.

kalabdel January 14th, 2021 07:49 PM

Thanks Jeremy. I haven't thought about PackML for a general system design. I will do some research into it.
I think most modeling languages now have state machine diagrams incorporated into it in some way.
I looked at Modelica and SysML and bumped into another language, OPM and wondered which is more worth of investing time to learn as they all seem to require learning both the modeling language/system and the IDE/Editor.


Cheers
Kal

PreLC January 14th, 2021 08:31 PM

Is PowerPoint an allowable answer?

Paullys50 January 14th, 2021 09:08 PM

I've become dependent on UML Sequence diagrams. I find they make it very easy to outline sequences and interactions that occur within the PLC as well external to the PLC such as PLC to PLC, PLC to SCADA, SCADA to DB, process interactions...etc without much of a time commitment.

I'm using them to model at a high-level, they make it easy for me to document my thoughts as I breakdown a process and my colleagues and clients usually pickup the intentions fairly quickly from a simple diagram.

After I've flushed out the high-level concepts with UML and it's time to go deep then I'll switch to a sequential function chart which I just use Excel to document all the specifics, typically just do this for outlining PLC code then I can hand it over to someone to program if I need to.

Paullys50 January 14th, 2021 09:09 PM

Quote:

Originally Posted by PreLC (Post 873895)
Is PowerPoint an allowable answer?

I've been known to use Power Point plus animations to draft HMI/SCADA screens ;)

kalabdel January 14th, 2021 09:10 PM

Quote:

Originally Posted by PreLC (Post 873895)
Is PowerPoint an allowable answer?






I've used power point very few times and that was for presentation of products or services; mostly. I'm not sure how easy it is to create different diagrams with it.



PowerPoint is an editor and it's a choice to use it to do whatever one's inclined to do with it. SysML, PackML and the rest of them, and there are quite a few, are considered system design/modeling "languages". A system of diagrams and methods, which may or may not include code.

FSM can be drawn using any editor one wishes to.

kalabdel January 14th, 2021 09:13 PM

Quote:

Originally Posted by Paullys50 (Post 873898)
I've become dependent on UML Sequence diagrams. I find they make it very easy to outline sequences and interactions that occur within the PLC as well external to the PLC such as PLC to PLC, PLC to SCADA, SCADA to DB, process interactions...etc without much of a time commitment.

I'm using them to model at a high-level, they make it easy for me to document my thoughts as I breakdown a process and my colleagues and clients usually pickup the intentions fairly quickly from a simple diagram.

After I've flushed out the high-level concepts with UML and it's time to go deep then I'll switch to a sequential function chart which I just use Excel to document all the specifics, typically just do this for outlining PLC code then I can hand it over to someone to program if I need to.


Thanks, that was very helpful as it pretty much mirrors what I'm looking.


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