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Problem with FC LT_BT - Siemens Library

Created by: layudhi at: 3/31/2012 1:36 PM (14 Replies)

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3/31/2012 1:36 PM	Rate (0)
layudhi Posts: 60 Rating: (1)	Hi All, I have a problem regarding the use of FC LT_BT from Simatic Manager Library On my case, i use this FC to convert my Local time to Base time with correction from Rule DB (GMT + 8) because my S7 315 PN/DP CPU didn,t have capability to convert it by it self after sync from my NTP Server The problem is, i have to increase my PLC Scan-time monitoring up to 500ms because of it. (On default setting, it only takes 150ms). Without increase the Scan-time monitoring, my plc would going to Stop My question is, 1. how to manage with this FC, so i can maximize my PLC Scan-time Monitoring back to 150 ms again ? 2. is there any other way to convert local time to base time without use this FC ? Regards, Layudhi
layudhi Posts: 60 Rating: (1)	Last edited by: layudhi at: 3/31/2012 1:39 PM
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4/2/2012 7:35 AM	Rate (0)
Aret Posts: 2348 Rating: (262)	Hello. Answer 2nd question first) 2) You can exclude Siemens block and write your own. 1) Actually such things shouldn't happen - can you upload your code here?How many times you call this FC?
Aret Posts: 2348 Rating: (262)
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This contribution was helpful to 2 thankful Users hdhosseini layudhi

4/3/2012 12:14 PM	Rate (0)
layudhi Posts: 60 Rating: (1)	Thanks Aret, So, i will start to make my own code - I put it on main cycle, so it will be executed every time. I have tried to put it on OB30, but my other function goes wrong (inconsistency scan time, i guest). I use indirect addressing and indirect typical for my Object, and with execute the Function in OB30, all my Indirect typical didn't execute properly. - Here i attached my FC in pdf, Regards Layudhi Attachment FC1.pdf (147 Downloads)
layudhi Posts: 60 Rating: (1)
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4/3/2012 4:38 PM	Rate (0)
Aret Posts: 2348 Rating: (262)	If you call FC1 inside OB1 ocne i can see nothing wrong with your code, which can lead to increase of cycle time. Can you comment everything except calling FC1 and test what cycle time it shows? Its neede to determine which block leads to big cycle time.
Aret Posts: 2348 Rating: (262)
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4/5/2012 12:32 AM	Rate (0)
layudhi Posts: 60 Rating: (1)	Aret If you call FC1 inside OB1 ocne i can see nothing wrong with your code, which can lead to increase of cycle time. Can you comment everything except calling FC1 and test what cycle time it shows? Its neede to determine which block leads to big cycle time. I agree with you, nothing wrong with FC1 at all. But, my problem is on the Network-10 where i call FC62 [Convert Local Time to Base Time]. My scan time increase when i call this FC, but will back to normal (7 - 10ms) when i bypass the FC
layudhi Posts: 60 Rating: (1)
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4/5/2012 7:17 PM	Rate (0)
SteveA Posts: 297 Rating: (41)	Instead of calling FC62 every scan, what if you call it once a second, since the time will only change every second? Then, maybe one scan a second will be long, but the average scan time will be acceptable. HTH, SteveA
SteveA Posts: 297 Rating: (41)
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4/6/2012 12:01 AM	Rate (0)
layudhi Posts: 60 Rating: (1)	Hi Steve, I had already tried before, i put the FC62 on OB30 which is scan every second. But it didn't solve my problem. The average scan time was increasing, just like before. Because of this i got another problem. My other function which used indirect addressing were not work properly
layudhi Posts: 60 Rating: (1)
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4/6/2012 8:46 AM	Rate (0)
Aret Posts: 2348 Rating: (262)	I got only 1 suggestion besides writing your own code - try to separate NW10 into 2 pieces - 1st with READ_CLK, 2nd with LT_TO_BT.
Aret Posts: 2348 Rating: (262)
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4/6/2012 9:34 AM	Rate (1)
BeVee Gold Member Joined: 7/18/2011 Last visit: 6/9/2023 Posts: 521 Rating: (88)	Hi layudhi, I found this in help text of FC LT_BT: Call Environment Internally, FC LT_BT uses the following functions of the S7 standard library – IEC Function Blocks. These functions must be loaded in your project with the numbers shown here. FC1 (AD_DT_TM), FC3 (D_TOD_DT), FC7 (DT_DAY), FC12 (GE_DT), FC23 (LT_DT), FC35 (SB_DT_TM) Did you load all those blocks in your project too? You're calling FC LT_BT from FC1, but FC LT_BT is calling FC1 too ... Kind regards, BV

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4/6/2012 1:23 PM	Rate (0)
layudhi Posts: 60 Rating: (1)	BeVee Hi layudhi, I found this in help text of FC LT_BT: Call Environment Internally, FC LT_BT uses the following functions of the S7 standard library – IEC Function Blocks. These functions must be loaded in your project with the numbers shown here. FC1 (AD_DT_TM), FC3 (D_TOD_DT), FC7 (DT_DAY), FC12 (GE_DT), FC23 (LT_DT), FC35 (SB_DT_TM) Did you load all those blocks in your project too? You're calling FC LT_BT from FC1, but FC LT_BT is calling FC1 too ... Kind regards, BV Hi BeVee Yes, i had loaded that following Function into my project. and for the FC1(AD_DT_TM), i rename it because i had already had a FC1 Actually, the FC LT_BT had been working properly. i could convert my Local time to Base Time. But it increased my PLC Scan Time At the moment, i delete the FC LT_BT till i get another solution to convert Local Time to Base Time Regards, Layudhi
layudhi Posts: 60 Rating: (1)	Last edited by: layudhi at: 4/6/2012 1:28 PM
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