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johnny61

PLEASE give an example on sequencer

42 posts in this topic

Can someone please show me the a simple ladder diagram using a sequencer strategy such as : 1.fill up water in tank. 2.turn on motor 3.drain the tank Please help me.I really would like to know the basic step of using the sequencer.Thank

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THIS thread should help you with the basics of sequencers That post is more geared towards Logix5000 processors but the principle is the same for all AB sequencers. What controller are you using?

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Take a look at some of the sequencer examples in the download area: http://forums.mrplc.com/index.php?dlcategory=2

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Thanks for the advice but I still do not understand how to use it.I am using logixpro 500 simulator.Can someone please show the ladder diagram which use sequencer to: 1.fill up water in tank. 2.turn on motor 3.drain the tank I really do not understand how to use it.Please help me by showing the ladder diagram.thanks

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Ken gave you a link to some good samples of a sequencer in the download section. Did you view them? Can you be more specific about what part of one of the samples you don't understand?

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I'm sure someone will be glad to write some simple code with the application your after. I Like to sequence with a bit shift where most I think use the sql sqo function. Are your steps. Step_1 Fill Tank Step_2 Turn on motor Step_3 Drain Tank Give us more info.

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yes,those are my steps.Can someone please show the ladder diagram.I would like to know how to use the sequencer instruction in the ladder diagram.thanks

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What Smoke is trying to say is we need more information to help you with your sequencer. Ken has given you samples, is there a particular part that is giving you a problem? What is going to switch from one sequence to the next? Float switch, pushbutton, timer, alignment of the planets? Below is the simplest sequencer I can think of and will do exactly what you asked. Upon power up of the PLC, output 0 will turn on. A few microseconds later, output0 will turn off and output 1 will turn on. A few microseconds later output 1 will turn off and output 2 will turn on. And a few microseconds later output 2 will turn off. This does exactly the sequence you have requested but you are never going to see an output turned on since outputs are updated after the scanning of the ladder. Can you give use some more information or post your code and show us where you are having the problem?

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Great program with the given information, couldn't have done better, even with the planets aligned.... Edited by TechJunki

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maybe this would help: http://forums.mrplc.com/index.php?autocom=downloads&showfile=550 just wonder if instructor will like it...

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Well Panic Modes is a little more flexible than mine but with all those switches wouldn't mine be easier to troubleshoot?

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I am having problem with how to use SQO instruction.How can I use SQO to execuate the next step after the previous step in complete.

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Can you post a screen capture of your sequencer instruction or post your program preferable so we can see where your are it. It will help us find what is stumping you. Chances are it is in your data files but you still aren't giving us much. What are using to drive your sequencer? I use a SQC as shown below but you can use a single bit to play with till you get a grasp of the SQO

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thanks for the ladder diagram.I think I can understand a bit now.I will try to use it with my ladder diagram.By the way,I just download a RSS file,how can I open it?I am using logixpro 500 simulator which can not open the file.

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What is Logixpro 500 simulator? Is that like RsEmulate 500?

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I got the PLC software from this webpage: http://www.thelearningpit.com/lp/logixpro.html

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I don't know for sure but I am going to take a wild guess that you can't. May be someone here can take Panic Modes download and convert it to a PDF for you then you can type it in. What file extension does logixpro give you the option of opening? Edited by TWControls

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PanicMode's program in pdf format: TANK_PROGRAM.pdf

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Looks good to me, I'll give you an "A" for it. Plus 10 extra credit points for good documentation.

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I know, the documentation was better than my example. Especially the alarms. I gave him my 4

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you are too kind... it seamed like homework so i decided to tease him a bit with complete program but - without using what i tought his teacher is probably asking for (SQO). i guess i was right...

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Your first mistake is using a coil at the start of rung 2, in SLC500 this is not allowed, coils must always be at the right of the rung, you can not series coils or other output instructions either (timers, maths etc).

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I know we all want to try and compliment one another, but where in this program does N7:0/0 get set or more to the point where does N7:1 get its first 1. This program would never start. Might I suggest we replace the add with a multiply by two, eliminate n7:1 all together and use only n7:0 and reset to 1 rather than 0. Check out this second edition please. TANK_PROGRAM_2.zip

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Do you not have help files or examples for SQO and SQC in the program youa re using. The RSlogix examples I saw made it fairly clear that the file and destination are not to be the same. Your Sequencer will need three steps therefore you will need to false to true transition the SQO instruction three times. For the sake of discussion change your SQO instruction to use a File of N17:0. In this case you have the following actions. Step 1 - SQO copies N17:0 masking the bits designated by the mask entry to N7:0. Step 2 - SQO copies N17:1 masking the bits designated by the mask entry to N7:0. Step 3 - SQO copies N17:2 masking the bits designated by the mask entry to N7:0. and sets R6:0.DN true. Now for the SQC command the function is similiar. If we use N17:0 for File, and R6:1 for control so as to not overlap the SQO. we get the following. Step 1 - SQC compares N17:0 masking the bits designated by the mask entry to N7:0. It then sets the FD bit of R6:1 if the entries agree. Step 2 - SQC compares N17:1 masking the bits designated by the mask entry to N7:0. It then sets the FD bit of R6:1 if the entries agree. Step 3 - SQC compares N17:2 masking the bits designated by the mask entry to N7:0. It then sets the FD bit of R6:1 if the entries agree. Hope this helps you clean up your sequencer portion. Your program should also be giving you and error for the use N7:0/1 as an output in an input position. Also note that o:2/1 needs it's own rung since it will only be on for one scan the way you ahve written it. If I can ask what is the final end use of this program.

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