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Old October 14th, 2003, 01:18 PM   #1
poiuy
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Recipes and RSView32

I'm making a machine which makes mixtures of fluids pumped from 16 reseviors. The operator interface I'm looking to have will have a scrollable list of mixture names and an on-screen button which will activate the correct pumps for X amount of time in order to pump the correct amount of fluid. Each mixture is independant, meaning that there are no batch runs. I'm using a SLC 5/01 processor connected via a PIC module and I want to run the interface on the laptop I'm programming from. I was thinking of using RSView for the interface, but I thought I'd ask for software recommendations. Also, could someone point me in the direction of software tutorials that would help in programming this kind of thing? Thanks, Chris
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Old October 20th, 2003, 11:40 AM   #2
poiuy
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Bump. Still looking...
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Old October 20th, 2003, 02:28 PM   #3
Berni
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better plc

With Rsview, you can do everything but have you many recipe to do?

If yes, the best way to do is the Indirect Adressing. But, your plc don't do this.

5/03 and higher can do.

I think you should change your plc too. It will be more flexible.
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Old October 20th, 2003, 04:10 PM   #4
Allen Nelson
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Batching 101

poiuy:

Thanks for the bump. I had intended to reply, but didnt' have the time then, and eventually forgot about it.

There are some preliminary questions that need to be addressed before you can decide about the SCADA software (if any) and the PLC programming techniques.

First off, though, a brief tutorial:

S88, the ISA's standard for batching, defines a "recipe" of consisting of four seperate components.

The first is just "header" information (Recipe name, version, who/what/where stuff).

A second component to a recipe is "resources" (this is usually only applicable in complex systems where you can make a recipe in different tanks - does THIS tank have the components (size, heating/cooling capabilty, etc) to make the recipe.). For your application, I don't think you have to worry about this too much.

A third component of the recipe, and one that most people think of when they hear the word 'recipe', is the "formula". This is both the type of material, and the quantity.

The fourth component, often overlooked, but critical to us PLC-programmer-types, is the procedure - which ingredients get added in which order (if it matters).

Another thing to keep in mind when referring to a recipe is that energy is an ingredient (in the form of agitation, temperature, pressure) as well as time..

So my first question to you is: How many recipes will you have/be planning for?

The next question, related, is: Where do you want those recipes to reside; the PLC, in the SCADA, or in a Database? You are planning to have "a scrollable list of mixture names". Will those names be fixed, set in stone (electronically speaking), or will the operator have the ability to add / delete / copy / modify recipes?

If you store the recipes in the PLC, then you are limited by the PLCs memeory (which in a SLC 5/01, isn't very much). If you want to store some of the header information in the PLC (such as the recipe name), you may have a hard time getting the SCADA to build that "scrollable list" - it's just not how the SCADA is set to operate (and I'm not just talking RSView; iFix and Wonderware have similar difficulties). I'm not saying it can't be done, just that it won't be easy (or may not work quite the way you want. Easier would be to have a whole screen with, say, 20 recipe names, and a NEXT and PREVIOYS button to take you to another screen with another 20 names).

Storing the recipes on the PC is often better for larger systems, but then you've got the problem of getting them into the PLC. Do you give out the recipe piecemeal (like RSBatch, iBatch, InBatch, and all the other xBatch products do), and wait for confirmation that a "phase" is executed before giving out the next peice (in order to do transaction logging - (Another Question: Do you need transaction logging?)), or do you just dump the entire recipe into the PLC at once? Databases also can be complex to set up - getting the SQL calls right so that the data is saved and retrieved properly. It's much easier to do it in the PLC where all you need is a pointer and some indirect addressing (more on that in a bit)

Some SCADA packages have their own recipe system (which is supposed to be easier than using something like Microsoft Access, or a REAL database.

Other questions/things to think about:

How flexible does the recipe's sequencing need to be? Will all the ingredients be added in the same order (or not added, if the setpoint is zero), or will you need to sometimes add "A, then B", and other times add "B, then C, then A".

Again, will the recipes be set, by you, or do you need to have a "recipe edit" capablity? These are pretty limited usually, but again depend on your application. Basically they save and retreive the value of tags that are associated with a recipe to/from an internal database and display them on the screen/send them to the PLC. They might be good for your application. I generally don't use then because there's always some function that I need the recipe handler to perform that I can't make the canned application do.

Are your recipes scalable? That is, if an operator selects RECIPE X, which makes 1000 liters, can he adjust it so that the same formulation/sequence will be used, but only make 800 liters? But, if he scales the ingredient amounts, how does that affect the amount of agitation time? Would you only agitate for 80% of the recipe time, or would you do the whole time? Or something in between (what's the algorithm?)?

Does an individual recipe need to be "tweeked" prior to use? That is, the recipe calls for 100 liters of 25% caustic, but the caustic in the tank had an assay of 30%, so you anly need 83.3 liters in this batch. (There's a whole lesson on "Master Recipe" v "Site Recipe" v. "Working Recipe" - some other time. Search for S88.02)

Do you want the ability for the operator to "add a bit of this" to a batch, as a sort of "semi-auto" operation (select the ingredient, enter an amount, push the button and GO)? Not to make a whole batch this way, but to adjust things ("Hmmm, the pH is low, let's add just 4 liters of caustic").

Are your 16 reservoirs, and/or their piping, shared by any other system? What should happen if both you and the other system need it at the same time? For that matter, do you have more than one batch tank that you control drawing from these ingredients?



Berni is right about indirect addressing. Indiect addressing is a handy technique for doing this type of application. The SCADA changes the value of a pointer, and that pointer is used to store/retrieve the recipe information.

But even a SLC 5/01 supports Indexed addressing. It's not as flexible as indirect (although it's possible to break the data file barrier), but could be handy in your application.



This is just the tip of the iceberg. There's still more to consider once these questions are answered, before you can design a batch system.

Oh, to answer your question, RSView is as good as any interface for doing what you're attempting. I doubt you need the power of RSBatch, for example. I've done a dozen or so systems just like this, using RSView, Fix, Wonderware, even a Panelview (only 10 recipes, stored in PLC).

There are some subtle differences between how each's Recipe system works. Wonderware's is a touch better than RSView's, as I recall, but it should be adequate for your needs, if you go that way.

Good luck.
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Last edited by Allen Nelson; October 20th, 2003 at 04:14 PM.
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Old October 20th, 2003, 04:54 PM   #5
poiuy
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Thanks for the responses. I'll try to answer all the questions in turn.

I'm stuck using a 5/01. Nothing to be done about that. I'm actually doing this as a personal 'fun' project, and the 5/01 is free surplus from work. It was pulled from a customer site during an upgrade, and we're not going to ever install it at a new customer site, so I got it for free.

For a little insight, I'm building something informally called a barmonkey, essentially an electronic bartending machine. (I'm a college student ) I'm looking to have as many recipes as possible, but I can make do with 30 or so if thats all I can get.

I expect the recipes to reside in a database, although like I said, I'm pretty open to suggestion. You mentioned that some SCADA programs have their own recipe interfaces. It was my understanding that RSView32 has a built in recipe function of some sort, although I havn't had too much time to investigate.

I dont need the user to be able to easily edit the recipes, although every once in a while I might like to add/delete recipes based on what materials I have on hand. It might be useful to have an option for enabling/disabling recipes, but I'm not too worried about that for now.

The 20 recipes per page was another option I was thinking about, and the more I learn about HMI's, the more I'm convinced that will be the best method. I was hoping the recipe could be dumped into the PLC at once, but again, I'm not sure how this sort of thing works.

Sequencing is pretty much unimportant. Scaling would be nice, but it's a "someday" feature. As for the 'semi-auto' feature, I'm using the AB relay module to control the pumps, and it would probably be easier to have a row of push button switches in parallel with each relay in case someone wants to add a little more of some ingredient.

Thanks!
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Old October 21st, 2003, 08:42 AM   #6
Matthias von Zorn
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You can find 5/02 processors on ebay for cheap. I picked up a 5/02 a couple months ago for 20 bucks. They do add more functions, like PID. If you can get a 5/03, youll get things like SCP, but ive noticed they still go for a decent amount of money.
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Old October 1st, 2005, 02:26 PM   #7
mrmss
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Quote:
Originally Posted by poiuy
Bump. Still looking...
what do you guys mean by 'bump'?

Is this a USA thing?
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Warning: The dates in this calendar are closer than they appear
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Old October 1st, 2005, 03:33 PM   #8
Eric Nelson
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Quote:
Originally Posted by mrmss
what do you guys mean by 'bump'?

Is this a USA thing?
I don't know if it's just a USA thing. It's definitely an internet forum thing. By writing a response, the message gets 'bumped' to the top of the 'unread message' queue in hopes that people will look at it (again).

Typing the word "bump" in the reply is only because you have to type something. It simply lets others know that the poster is still looking for help.



-Eric
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