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Time Compare S7-315

Created by: genious2015 at: 1/8/2020 7:46 AM (9 Replies)

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1/8/2020 7:46 AM	Rate (0)
genious2015 Experienced Member Joined: 8/31/2016 Last visit: 7/16/2025 Posts: 92 Rating: (1)	I need block compare time, (S7-315) (I create block for run time it's output is real) I have 5 pump depend on work time ,select which one will work ( If I use real compare , what is block select which one has the lowest time and has 5 digital output) There is possibilty of pump fault
	Last edited by: genious2015 at: 01/08/2020 07:59:32 Last edited by: genious2015 at: 01/08/2020 08:00:26
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1/9/2020 9:12 AM	Rate (0)
Hati Platinum Member Joined: 9/21/2012 Last visit: 1/15/2026 Posts: 4848 Rating: (512)	genious2015 I need block compare time, (S7-315) (I create block for run time it's output is real) I have 5 pump depend on work time ,select which one will work ( If I use real compare , what is block select which one has the lowest time and has 5 digital output) There is possibilty of pump fault There are several posts about this same issue. Use the forum search to find answers.

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1/9/2020 1:11 PM	Rate (0)
genious2015 Experienced Member Joined: 8/31/2016 Last visit: 7/16/2025 Posts: 92 Rating: (1)	Hati genious2015 I need block compare time, (S7-315) (I create block for run time it's output is real) I have 5 pump depend on work time ,select which one will work ( If I use real compare , what is block select which one has the lowest time and has 5 digital output) There is possibilty of pump fault There are several posts about this same issue. Use the forum search to find answers. Can you provide me one of this post?

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1/9/2020 8:11 PM	Rate (0)
Hulzhex Platinum Member Joined: 8/25/2005 Last visit: 1/14/2026 Posts: 1162 Rating: (111)	Hello genious2015, hope with this search result you will get an idea how to solve your issue: compare time Good luck Sabine

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1/9/2020 9:03 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 1/5/2026 Posts: 6892 Rating: (1368)	Dear friends, I need block compare time, (S7-315) (I create block for run time it's output is real) I have 5 pump depend on work time ,select which one will work ( If I use real compare , what is block select which one has the lowest time and has 5 digital output) There is possibilty of pump fault I don't think it is like a simple time variable compare type of question in STEP 7. Pumps are crucial and sensitive rotary pieces of equipment in any plant. Selecting the next operational pump should happen , while the current pump is working. The selection is made based on minimum working hours of all 4 other pumps (MIN Selection) while it is electrically available (NO FAULT). MIN calculation is easily supported by STEP 7 basic library and finalize your selection with fail safe signal of pump electrical availability.In case of failure of your selected pump , run the criterion again. I hope it helps, hdhosseini
	Last edited by: hdhosseini at: 01/09/2020 21:08:31 Demo Channel on Youtube
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1/13/2020 5:33 PM	Rate (0)
Willybong Silver Member Joined: 2/11/2015 Last visit: 1/8/2026 Posts: 515 Rating: (36)	I suggest you do a function that order the pumps that are not running and not in alarm. Order them for hours by desc. A simple type of ordering is compare the first one with others, then the second, ... and establish an order. When you've to insert a new running pump, look at the table and enter the next one.

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1/29/2020 5:48 PM	Rate (0)
genious2015 Experienced Member Joined: 8/31/2016 Last visit: 7/16/2025 Posts: 92 Rating: (1)	hdhosseini Dear friends, I need block compare time, (S7-315) (I create block for run time it's output is real) I have 5 pump depend on work time ,select which one will work ( If I use real compare , what is block select which one has the lowest time and has 5 digital output) There is possibilty of pump fault I don't think it is like a simple time variable compare type of question in STEP 7. Pumps are crucial and sensitive rotary pieces of equipment in any plant. Selecting the next operational pump should happen , while the current pump is working. The selection is made based on minimum working hours of all 4 other pumps (MIN Selection) while it is electrically available (NO FAULT). MIN calculation is easily supported by STEP 7 basic library and finalize your selection with fail safe signal of pump electrical availability.In case of failure of your selected pump , run the criterion again. I hope it helps, hdhosseini Where can I find it on Step 7 library? Note: IO module not Fail safe , Normal IO module

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2/4/2020 7:07 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 1/5/2026 Posts: 6892 Rating: (1368)	Where can I find it on Step 7 library? Note: IO module not Fail safe , Normal IO module For pump control block , select from this Library . It has pump runtime in REAL data type that suits your case. https://support.industry.siemens.com/cs/ww/en/view/68679830 There is an input for motor protection that is NC.When it is false or unavailable ,remove it from the list or insert a max runtime on its list.MIN selection is FC27 from IEC LIBRARY in STEP 7. I hope it helps, hdhosseini
	Demo Channel on Youtube
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2/13/2020 3:48 PM	Rate (0)
Piotr.M Platinum Expert Joined: 6/24/2013 Last visit: 11/14/2025 Posts: 1696 Rating: (433)	if you need compare 2 reals use cmp >r ; >=r etc. if you need compare 2 Time variables use STL and L #time_1 L #time_2 >=D // use D comparator because Time internally is dint in ms

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2/13/2020 3:51 PM	Rate (0)
Piotr.M Platinum Expert Joined: 6/24/2013 Last visit: 11/14/2025 Posts: 1696 Rating: (433)	Hi Also make sure to use uneven timing (i.e. some pumps will run for longer time) This is to ensure they will not wear at the same rate (so they will not need to be switched OFF for maintenance at the same time) for example pumps 1,2 would run 2 x longer than 3,4,5 this way they will require maintenance at shorter intervals than 3,4,5 and you can maintain continuous operation (not all 5 pumps in maintenance at the same time)

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