Recipes

[tori69 0]

I am new with plc's. I have an assignment to program to simulate an automatic pizza making machine. The program will make 4 types of pizzas and I am supposed to use indirect addressing. Can someone help me please?

[Ken Moore 23]

Programming PLC's is just like any other assignment, first you have to define the goal. In this case before you can define the goal, you have to define the process. I suggest you write down in plain english, exactly how this operation works. Something like: Operator places a pizza crust at position A, which makes photo-eye 1, operator then selects one of four recipes by placing switch-1 in the corresponding postition, the operator depresses button-1, then if PE-1 is true and PE-2 if false, something happens...... You can't program a machine to preform a process, if you don't know what the process IS. Once you have completed the above, post your work, and we will help you along. Many times students get a hard time here and at other forums, we will not do your work for you, but we will help if you put forth some effort. We want you to learn from the process, and the only way that will happen is if you do it yourself with a little help over the high hurdles.

[tori69 0]

Thank you for the response. Yes you are right I missed that info. Like I said, the program will make four types of pizzas with different ingredients. There will be only one pizza in the machine at any given time. A conveyor belt will stop the pizza under each station for the required amount of time to apply the ingredients with 2 sec needed to travel to the next station. Station 0 will be for loading and station 6 for unloading. Pizzas will not stop at stations from which no ingredients are required. So I would have to use four different recipe files one for each pizza recipe. The type of pizza should be switch selectable and be selected before the cycle start PB is pressed. An active station number counter should be used to determine which station the pizza is under. Station# ingredient Cheese pizza Pepperoni pizza Deluxe pizzas Mushroom pizza 1 Pizza sauce 30g 30g 30g 30g 2 Cheese 50g 30g 30g 30g 3 Pepperoni 0g 40g 30g 0g 4 Green pepper 0g 0g 20g 0g 5 Mushrooms 0g 0g 20g 30g Since I never used indirect addressing before I have real trouble figuring this out. Any help would be appreciated. Thanks again.

[Ken Moore 23]

Depending on how you set up your program, the indirect addressing will most likely be used for quantites of each ingredient. Just for an example let's look at your third ingredient: You have: Pepperoni 0g 40g 30g 0g Now lets store these values, we will use N13:0 through N13:3. N13:0=0 N13:1=40 N13:2=30 N13:3=0 (This is just a simplified example, your code will be different) Now Let's assume your recipes are 0-3, and that you have a FIFO stack for each station, the third stations "current value" is located in N23:0 So when the pizza gets to station 3, the amount of pepperoni would be found in N13:[N23:0]. This tells the plc to go to File N13, and then offset the value found in N23:0. So....if N23:0 contained a value of 2, the plc would go to N13 plus offset of three (0,1,2), and the value would be.....30 One way to look at it is to plug in the value of the indexed address. N23:0 contains a 2 so N13:[N23:0] is equal to N13:2 Hoped this helped, and just didn't confuse you more. Maybe one of the more knowledgable members will chime in with a better explanation. Sometimes even though I understand a concept, I have a hard time explaining it to others. Ken

[tori69 0]

Thank you Ken. That will help a lot.

[rswolff 9]

sounds like you're taking a class....what good would it do if I told you how to do it....the teacher is trying to see how YOU do it with the information you have or have been taught.....

[TimWilborne 108]

Actually your quote is from Ken Moore who is excellent teacher, not a student.