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motor run hour meter

Created by: Tagolover at: 4/28/2009 4:26 PM (26 Replies)

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4/28/2009 4:26 PM	Rate (0)
Tagolover Gold Member Joined: 9/6/2008 Last visit: 10/29/2019 Posts: 1111 Rating: (78)	Hi all i have around 26 motor for which i have to calculate the number of hours run in SCADA. Now my problem is that i tried using the SFC 0 , 1, 2,3,4 for reading the system clock and calculating. and i found that the number of times you can use these blocks is very limited I have used CPU 315-2dp , with 256 KB mmc card
	TAGOLOVER
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4/28/2009 5:38 PM	Rate (1)
Denilson Pegaia Platinum Member Joined: 9/23/2005 Last visit: 12/8/2019 Posts: 3750 Rating: (1039)	Hi, sometime I wrote a article that would be published as FAQ http://support.automation.siemens.com/WW/view/en/26116927 Take a look at the last examples.
	Denilson Pegaia Siemens Industry Sector Technical Support
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This contribution was helpful to 4 thankful Users Tagolover Ayman Elotaify EIC_CONTROL M.Abzadeh

4/29/2009 9:44 AM	Rate (0)
uel123 Gold Member Joined: 1/29/2006 Last visit: 12/8/2019 Posts: 356 Rating: (44)	Tagolover ... i have around 26 motor for which i have to calculate the number of hours run in SCADA. Hey, tagolover! At first, let me say, that I would rather do it in PLC, not in SCADA. In CPU, I wouldwrite a small FB, which will (must!) be called in precise time- defined periods (u can use OB35 or simple clock memory; it depends on desired resolution and other resources....). For each call, you simply test, if your motor is running. If it is, you add a increment of time (= periodbetween 2 calls of your FB)to your hours run....... have fun! uel123

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4/29/2009 10:46 AM	Rate (0)
Tagolover Gold Member Joined: 9/6/2008 Last visit: 10/29/2019 Posts: 1111 Rating: (78)	Dear pegaia Thank you for the post, But can you tell me that if i can use this program any number of times. Without the worrying about the CPU Best regards
	TAGOLOVER
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4/29/2009 5:19 PM	Rate (0)
Denilson Pegaia Platinum Member Joined: 9/23/2005 Last visit: 12/8/2019 Posts: 3750 Rating: (1039)	Hi, the example 5 and 6 has no system limitation. Naturaly, the code take places on the memory but you can measure how many different times that you want.
	Denilson Pegaia Siemens Industry Sector Technical Support
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4/29/2009 6:27 PM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 10/29/2019 Posts: 701 Rating: (88)	Hello, and it will increase the cycle time because of multiple SFC calling which can be so slow with S7-300 CPUs. When you call the block for instance one hundred times. Regards Sydney

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4/29/2009 9:26 PM	Rate (0)
Denilson Pegaia Platinum Member Joined: 9/23/2005 Last visit: 12/8/2019 Posts: 3750 Rating: (1039)	Hi, the call of the SFC/SFB take time,in the same mode as any logical. I don't measure the runtime of this blocks, but my experience with SFC64 is that theruntime is not proibitive (55 to 0,8MICRO seconds depending of the CPU).
	Denilson Pegaia Siemens Industry Sector Technical Support
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4/29/2009 11:22 PM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 10/29/2019 Posts: 701 Rating: (88)	I wrote about SFC1/SFC64 in S7-300. According to instruction list for the CPUs S7313to315 it is 60 resp. 50 us so hundred times call should take about 6 resp. 5 ms but I don't believe in this numbers.Based on my experiencesthese numbers are just for orientation and normallymultiple calling ofthese SFCstakes longer time, another thing is that the execution times are pretty different beetween CPUs of the same family, for example the S7315-2PN/DP is much faster then S7315-2DP. For a good behaviour we make the time difference(using TIME_TICK) at the beginning of cycle which is then passed as the TIME data type to various blocks. Inaccuracy is in principle the same because normallythe running signal is taken from the process image so if you have one time difference for all or make this for each signal independently the result accuracy is always relative to cycle time. If theSFC calling and difference determination for each signal independently (which means longer cycle time)is taken in account it causes worse results. Regards Sydney
	Last edited by: Sydney at: 4/29/2009 11:25 PM
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4/30/2009 7:29 AM	Rate (0)
Tagolover Gold Member Joined: 9/6/2008 Last visit: 10/29/2019 Posts: 1111 Rating: (78)	Thank you to all.. I shall check the program given in example 5 and 6 and get back to you all .. Thanks once again
	TAGOLOVER
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4/30/2009 10:31 AM	Rate (0)
uel123 Gold Member Joined: 1/29/2006 Last visit: 12/8/2019 Posts: 356 Rating: (44)	Hey, Guys! I am reading your discussion about measuring time, for "motor run hour meter" (by tagolover). Proposed methods (Pegaia) are excellent, with highest possible resolution for time measurement onCPU. Estimatedresolution of measured working time would be the same, as OB1 cycle time (few miliseconds (?)....). The question is, if such precise measurement is really needed for "motor run hourmeter"? Tagolover: do your motors really work for (yust for example!)67 ms everyhalf of second? In that case, you really need such precise measurement, as proposed from Pegaia. In my experience, motor run hour meters are tipically for systems with larger motors (just for example), systems withmore pumps, where 2 or more pumps are in system and at least one is 100% reserve. Users usually want to "rotate" use of pumps, that after a longer period of time, all pumps have appr. the same working hours. Other common use of run hour meter is, if you have to do some maintainance on your equipment after a certain amount of working time is reached (let say, every 10000 hours you shold do something....). In such application, motor is allways started for longer period of time (few hours or more!), and such precise method of measurement is not needed, simple methods (with resolution of 1s f.e.) are quite good and efficient. Anyhow, allways have fun and try to keep it simple! uel123

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