Logic Diagram Software

It surprises me that this isn't common rather than being something we fight about.
The reality is that having this information in a clearly visible format is priceless for maintenance and even operators. Granted, there's an element of education required for operators, but we really should strive to end the days of "looking in the plc" for what's stopping a machine. The process industry has as a standard a display of interlocks precisely for this. Somehow machinery doesn't think it's necessary.

Diagrams like this should communicate to non-programmers what the expected operation of the equipment/process will be. It should be used as an engineering document to tell others how to program it, and/or be used in conjunction with FAT/SAT testing to ensure that ladder logic you wrote does what you expect it do.

I agree to the extent that most programming languages are **** at relaying the information to non-programmers. SFC and if used with process blocks FBD (or the Siemens CFC) along with a strict variable naming standard is a lot better than some traditional flowcharts. Remember that it's tricky to display parallel or selection tasks in flowcharts. In SFC, this is accounted and takes little to explain that 2 lines is parallel and 1 line is selection.
I'm doing that now with the process guys and they not only love it, but want it for operations and as the documentation of the process recipe.
 
Why not program in ladder and print it out? Then your logic is there for anyone to see.

+1
That was my thought. I worked at a water utility in the 2000's with all PLC 5. We had hard copies of the logic for most of the equipment, mainly because some dufus would make a few changes and not upload it to the server when they came back to the shop. Then when the next person went out to that particular site and processor, they had no annotation.
 
I think the problem lies mainly with the softening of requirements due to very flexible hardware and software platforms. These types of diagrams were absolutely necessary back when relay circuits, timers, counters and setpoint controllers controlled the automation. The people specifying and designing the machines needed to know EXACTLY what the machine should do so the right number and type of devices could be installed and wired. It gets really painful when you realize you left out a relay or you had to rewire or add contacts to an existing relay. PLCs have made it much easier to design the process on the fly and easier yet to modify if something doesn't work in the right order. I feel this has led to the inability for some customers to even specify exactly what they want at every step. They simply describe the end results. I have seen this for years. The "seasoned" process and control engineers fully think out the whole process before starting. The newer ones don't always think that far ahead before starting the design. It is kind of like when calculators became handheld. People stopped thinking about the mathematical processes and just concentrated on the buttons to press.
 
I think the problem lies mainly with the softening of requirements due to very flexible hardware and software platforms. These types of diagrams were absolutely necessary back when relay circuits, timers, counters and setpoint controllers controlled the automation.

I would argue flexibility requires some form of engineering prior to writing any code. Having a diagram/document to communicate intent is an essential requirement before you can start coding. Too many people overlook the design process and jump right into logic which is why people burn out on the job-site.

Relays, Timers, Counters...etc have all been replaced with data, reporting, plc to plc compunction and SCADA/MES/ERP interface definitions in modern system. I've wasted days, weeks, months of my life in meetings and refactoring code because a system I need to interface can't provide a basic diagram of what I can expect their system to do and how to interact with it.

And no an Excel spreadsheet of tags doesn't tell me when I can expect them to be true/false or change in value.

For giggles, attached is the progress of printing my current ControlLogix project.

printStatus.PNG
 
I have never used the feature, I had to check now to be sure it is there.

I, being too cheap to buy MS Office, use the free Ultra Office. It has, along with Word-ish and Excel-ish programs, Draw that creates flow charts.

On my home PC I have Libre Office and I think it does flowcharts also, but again never used it.
 
I've done many logic flowcharts with SmartDraw software. Worked good for me. I like flow charts because it removes ambiguity from logical process. Colleagues did not embrace and said all they needed was a functional description. To me that is total BS. Using flow charts, you quickly find that a functional description is nothing but positive logic and completely ignores the negative. I.E., in flow chart, the "No" point or 'exit' of a decision diamond has no destination. Flow charting uncovers a bunch of sins if done right. Just cost money because it takes time is all.
 
I have used SmartDraw in the past, but now I do everything in dwg files

The dwg format is just more universal, and covers all my needs.

I skipped Autocad, since there there licens politic is out of touch, with the few drawings I make a year, so now I use ActCAd
 
I include Grafcet diagrams with user manuals upon request. I just use AutoCAD. The Grafcet standard is mostly a bunch of boxes, lines and floating text so it plays well with CAD drawing software. Standardized blocks make doing those a joke.

I was taught to use Visio in school and never really got the hang of using that software to make diagrams that actually looked good. I wanted to off myself every time I used Visio, to the point where I would scour the requisites to see whether I could justify submitting diagrams drawn by hand.
 
I like Visio. We started using it 2 years ago for our Electrical CAD drawings, since I have used it for about everything(many different kinds of drawings) very simple. I built most of my symbols library for Electrical controls(hardest and most time consuming part), however built in to Visio there are a lot of symbols and I think early on it is what people used for flowcharts, it has an very good sets of symbols include for flowcharting. After a few drawings I had a pretty good symbols library(they call it stencils, create a symbol save it to a stencil you can have many different stencils call up what ever stencil you want with a drawing, very easy.

Sure there are better programs and ones that cost a lot more that can do more things but for us this was the right thing(small company not a lot of drawings)(use to use ACAD with another package for electrical but huge money to keep this up.

I will admit at first I thought it was hokey compared to AutoCad but that because I did not know, once setup it is ok.

I would not use for drawings with a lot of dimensioning it is very weak for that, it works but weak.
 
It surprises me that this isn't common rather than being something we fight about.
The reality is that having this information in a clearly visible format is priceless for maintenance and even operators. Granted, there's an element of education required for operators, but we really should strive to end the days of "looking in the plc" for what's stopping a machine. ...

I agree with this. It can be very helpful to the programmer. This is especially true if there are details I might not fully understand about the machinery or process. I can sit with experienced operators who can help me refine the functional diagram of the operation before I waste time guessing or assuming what the steps and transitions are supposed to be. It can also help me visually see and apply the "what ifs" that I might not think of just working through the code using experiences and past practices as my guide.

In the water industry, it is rare that I come across a sequence complex enough to justify the time investment to do all this planning. And when I do come across that sort of process, I am often working with operators who don't have a full enough understanding to help me! But having a flow chart that a team of various skill sets can understand and analyze is still a highly valuable tool.

I don't have any go-to software for this. A stack of tabloid paper and a pencil is where I start, and once it's refined enough, I use Cad software to memorialize it.
 

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