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Alternate two pumps with different level of start/stop

Created by: roberto.zeni at: 1/2/2021 8:03 PM (12 Replies)

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1/2/2021 8:03 PM	Rate (0)
roberto.zeni Experienced Member Joined: 4/9/2009 Last visit: 10/11/2024 Posts: 68 Rating: (1)	Hi guys, I have this situation: Q1 Command Start P1 Q2 Command Start P2 I1 Level 1° pump I2 Level 2° pump I3 Fault P1 I4 Fault P2 I would like to implement this logic: The pumps must be active from the two levels (I1 and I2) alternatively In case of fault of Px the others pump must be active In case of two level ON all available pumps must be active but when one level return to off the pump to be switched off is the pump that had been started from this level (i have problem to implement these cases...) Sequence examples (not considering the Faults): Example 1 - Case with only 1 level active at time: I1 = Off and I2 = Off Q1 = Off and Q2 = Off I1 =On Q1 =Onand Q2 = Off I1 = Off Q1 = Off and Q2 = Off I1 =On Q1 = Off and Q2 =On I1 = Off Q1 = Off and Q2 = Off I2 =On Q1 =Onand Q2 = Off I2 = Off Q1 = Off and Q2 = Off I2 =On Q1 = Off and Q2 =On I2 = Off Q1 = Off and Q2 = Off Example 2 - Case with 2 level active at time: I1 = Off and I2 = Off Q1 = Off and Q2 = Off I1 =On Q1 =Onand Q2 = Off I2 =On Q1 =Onand Q2 =On I2 = Off Q1 =Onand Q2 = Off Example 3 - Case with 2 level active at time: I1 = Off and I2 = Off Q1 = Off and Q2 = Off I1 =On Q1 =Onand Q2 = Off I2 =On Q1 =Onand Q2 =On I1 = Off Q1 = Off and Q2 =On Any idea or sample? Thanks

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1/2/2021 8:18 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 11/18/2024 Posts: 34239 Rating: (4263)	Please use search function of the forum. There are so many examples for pump control. Pump

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1/2/2021 8:47 PM	Rate (0)
roberto.zeni Experienced Member Joined: 4/9/2009 Last visit: 10/11/2024 Posts: 68 Rating: (1)	Hi, first of all thank for reply! I have already searched in the other posts but I have not found cases in which there was talk of the control of pumps in alternation with two different levels which, among other things, can also be activated together by turning on both pumps. As for the normal alternation and the simultaneous command I would have already implemented a software but I cannot manage the switching off of the correct pump when, from two active levels pass to one (I should switch off the pump that has been switched on from the level that becomes off but I can...) Thanks and Best Regards Roberto

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1/2/2021 8:59 PM	Rate (3)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 11/18/2024 Posts: 34239 Rating: (4263)	I also did not write that you will find a solution that is exactly tailored to your situation under the examples. From this I can only conclude that you would like to have a finished program delivered. Do you expect others to do your work and you will collect the money for it?

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1/2/2021 10:06 PM	Rate (1)
roberto.zeni Experienced Member Joined: 4/9/2009 Last visit: 10/11/2024 Posts: 68 Rating: (1)	Dear ixo65, it'better not answer to you... If you had read my first post carefully you would have understood that my question was only oriented to a particular problem and not to have the complete software (if you read well it says that the software has already been done except for the fact of switching off of the pump in case of lack of the second level). However, don't waste your precious time tot answering me... Don't worry, luckily I don't need your software to live... Thanks anyway a lot for your help

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1/3/2021 3:49 AM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 11/18/2024 Posts: 34239 Rating: (4263)	Hello roberto.zeni, I read your opening post. It just says what situation you have and what you want a program to do. That you already have a program, nothing is written about it. If you have a program that doesn't work quite the way you want it to, please upload it in zipped form. Then we can analyze it and make any necessary adjustments.

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1/3/2021 11:29 AM	Rate (0)
roberto.zeni Experienced Member Joined: 4/9/2009 Last visit: 10/11/2024 Posts: 68 Rating: (1)	Hi ixo65 thanks for the clarification, probably my first post wasn't clear. In attachment you can see the program already developed and tested. Some notes: - I1 = Fault P1 - I2 = Fault P1 - I3 = Common fault - I4 = Level 1 - I5 = Level 2 - Q1 = Start P1 - Q2 = Start P1 The level 1 and level 2 can be activated in any sequence, In my opinion the logic developed should already work for alternation, switchover in case of fault, activation of all pumps available in case of both command level, etc. I would like to solve theese two problem: PROBLEM 1 (Shutdown sequence) First pumping cycle Level 1 = On --> P1 On (ok) Level 2 = On --> P2 On (ok) Level 1 = Off --> P2 Off (not ok - pump 1 should turn off) Second pumping cycle Level 1 = On --> P2 On (ok) Level 2 = On --> P1 On (ok) Level 2 = Off --> P2 Off (not ok - pump 1 should turn off) PROBLEM 2 It seems that when switching from two active levels (both pumps on) to only one active level, for one program cycle both pumps are switched off... The same logic implemented in S7-1200 doesnt have this stange behavior. Thanks and Best Regards Attachment AlternationTest.zip (333 Downloads)

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1/3/2021 4:14 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 11/18/2024 Posts: 34239 Rating: (4263)	Even at the risk of being misunderstood: Quote: "The same logic implemented in S7-1200 does not exhibit this strange behavior." I may not be able to judge that, because I do not know the S7 program. But it's not the same programming language. And it goes without saying that you cannot program with LSC in the same way as with STEP 7. So it cannot be the same programming.

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1/3/2021 5:08 PM	Rate (0)
roberto.zeni Experienced Member Joined: 4/9/2009 Last visit: 10/11/2024 Posts: 68 Rating: (1)	Hi ixo65, first of all thanks for reply and dont worry for possible misunderstandings Yes, I know that the programming of an S7-1200 PLC is different from a LOGO! but, in principle, if you use LADDER programming with only parallel and serial logic gates it is quite simple then transform the logic from S7-1200 to LOGO!. However, if you are interested, the TIA Portal project is also attached. The big problem, however, I think it is number 1 mentioned in my last post because, for number 2, I think that in the real PLC it shouldn't even have time to really shut down the pump Thansk and Best Regards Roberto Attachment TestLogo.zip (286 Downloads)

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1/4/2021 4:06 AM	Rate (2)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 11/18/2024 Posts: 34239 Rating: (4263)	In my opinion, the problem is the marker M3, which has a HIGH signal when both levels have a HIGH signal and then switches off one level. Both pumps are then switched off in the same cycle. The priority pump can only be switched on again in the next cycle, since the output of the non-priority pump must report a LOW signal. A typical cycle problem. See attached video... Attachment Cycle problem.zip (324 Downloads)

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