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scan cycle time is slow of s7-300

Created by: ksazzad-ksrm at: 7/1/2013 2:22 PM (12 Replies)

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7/1/2013 2:22 PM	Rate (0)
ksazzad-ksrm Posts: 4 Rating: (0)	To whom it may concern Dear all, i work with a system where s7-400 & s7-300 used together. i got s7-400 scanning is fast but in case of s7-300 it is too slow and sometime it too slow that interrupt the process when i give scan. i checked scan cycle time for s7-300 & s7-400 is 150ms. for data transfer we use optical fiber & profibus cable. it is killing me to find out the solution .... can anybody help me. Md Sazzad Bin Rashid Electrical Engineer KSRM steel plant limited
ksazzad-ksrm Posts: 4 Rating: (0)	Last edited by: O_Moderator at: 7/1/2013 8:32 PM contact data deleted Last edited by: ksazzad-ksrm at: 7/1/2013 2:23 PM
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7/1/2013 2:29 PM	Rate (0)
viralpatel Silver Member Joined: 11/18/2010 Last visit: 8/5/2022 Posts: 523 Rating: (32)	ksazzad-ksrm To whom it may concern Dear all, i work with a system where s7-400 & s7-300 used together. i got s7-400 scanning is fast but in case of s7-300 it is too slow and sometime it too slow that interrupt the process when i give scan. i checked scan cycle time for s7-300 & s7-400 is 150ms. for data transfer we use optical fiber & profibus cable. it is killing me to find out the solution .... can anybody help me. Md Sazzad Bin Rashid Electrical Engineer KSRM steel plant limited 150 ms is to slow speed. are you getting watch dog timer error? even heavy loaded CPU has hardly 20-30 ms scan time can you tell which type logic ,communication is used by s7 300 PLC viral patel
	Last edited by: O_Moderator at: 7/1/2013 8:34 PM
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7/1/2013 3:43 PM	Rate (0)
TEBANCH Silver Member Joined: 3/25/2008 Last visit: 1/28/2022 Posts: 232 Rating: (20)	ksazzad-ksrm To whom it may concern Dear all, i work with a system where s7-400 & s7-300 used together. i got s7-400 scanning is fast but in case of s7-300 it is too slow and sometime it too slow that interrupt the process when i give scan. i checked scan cycle time for s7-300 & s7-400 is 150ms. for data transfer we use optical fiber & profibus cable. it is killing me to find out the solution .... can anybody help me. Md Sazzad Bin Rashid Electrical Engineer KSRM steel plant limited Hello, Please indicate which CPU are you using and also mention if is this a new system or a system that was already running. Please take a look to the attached images, try to post the same but for your PLC, to see how much memory has been used, and see the actual scan cycle time. Regards. Attachment ScanMemory.zip (691 Downloads)
	Last edited by: O_Moderator at: 7/1/2013 8:35 PM Keep working!
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7/1/2013 5:48 PM	Rate (0)
MRG Bronze Member Joined: 1/20/2008 Last visit: 9/15/2024 Posts: 120 Rating: (7)	Dear ksazzad-ksrm Do you have any SCL or Graph function in your program? may be something wrong inSCL or graph source. Regards, MRG

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7/1/2013 5:57 PM	Rate (0)
MRG Bronze Member Joined: 1/20/2008 Last visit: 9/15/2024 Posts: 120 Rating: (7)	Hello again, what about your load and work memory! If size of your program is more than work memory, your cycle time will be increase. Please check size of your program. Also check diagnostic buffer, you get only "cycle time exceeded"or another event. Regards, MRG

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7/2/2013 5:17 PM	Rate (0)
SolutionFinder Posts: 559 Rating: (87)	Dear ksazzad-ksrm, Do you have communication between these two PLCs or You are comparing with two different systems?
SolutionFinder Posts: 559 Rating: (87)
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7/3/2013 7:01 PM	Rate (0)
ksazzad-ksrm Posts: 4 Rating: (0)	Dear all, thanks for reply. i attached a file where i put photos of my project. regarding these photos can anybody help me what to do. pls Md Sazzad Bin Rashid Electrical Engineer KSRM steel plant limited Attachment picture of my project.zip (410 Downloads)
ksazzad-ksrm Posts: 4 Rating: (0)	Last edited by: ksazzad-ksrm at: 7/3/2013 7:05 PM
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7/3/2013 7:19 PM	Rate (0)
legacy support Silver Member Joined: 7/15/2008 Last visit: 1/23/2024 Posts: 382 Rating: (44)	ksazzad-ksrm Dear all, thanks for reply. i attached a file where i put photos of my project. regarding these photos can anybody help me what to do. pls Md Sazzad Bin Rashid Electrical Engineer KSRM steel plant limited Hello How many of you profibus slaves are actually online and avaliabe. If you have profibus slaves configured in you HW but they are not avaliable on the bus this will cause the Error OB to be called and therefore increases you scan time. as mentioned also check if you have other errors that call Error OB's I have a 400 system with 108 drives / motors on profibus running at the same time and my scan time is 11ms. Regards / m.f.g

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7/4/2013 4:27 AM	Rate (0)
ksazzad-ksrm Posts: 4 Rating: (0)	Dearlegacy support i understand your note about profibus slaves. in my project there only 15 profibus slaves and all available with hw configuration. but my systems scan cycle time is too slow so what can i do? Md Sazzad Bin Rashid Electrical Engineer KSRM steel plant limited
ksazzad-ksrm Posts: 4 Rating: (0)
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7/4/2013 5:45 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	Hello, For an improvement I suggest categorizing tasks you are executing for fast,medium and slow processes.Fast processes or critical cases should be handled in a fast scanning cyclic interrupt and for a slow process, less execution time is necessary.This is matter of scheduling tasks in different cyclic interrupts of CPU and check the scan time in each case. Best regards Hamid Hosseini
	Demo Channel on Youtube
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