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Integer input range of analog module

Created by: Pandiani at: 10/2/2007 2:34 PM (16 Replies)

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10/2/2007 2:34 PM	Rate (0)
Pandiani Bronze Member Joined: 10/31/2005 Last visit: 11/29/2023 Posts: 321 Rating: (30)	Hello to all, I tried to search the forum, but I coudn't find real explanation why range with analog S7 300 (400) is from 0 to 27648 (assuming unipolar signal 4-20 mA). I cannot figure out why is upper limit 27648 (100 %), why not 27649 for example? I know the story about overflow and similar, but I'm really curious why it is made 0 to 27648? I've searched all other forums, and found this topic is discussed many times but it seems nobody knows for sure... Thank you for the answer...

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10/3/2007 11:37 AM	Rate (2)
Ates Posts: 198 Rating: (17)	in generally we use 13 bit cards which is 2^13 = 8192 but there are also 14 bit cards = 2^14 = 16384 and 2^15 = 32768 which is the last point of card .. 27648 - 16384 = 11264 16384 / 11264 = 1.454545 .45 is for overflows .. so in the end i dont know :) why is a cd 65 min ? because the one who invented it likes mozarts x senphony which is 65 min :)
Ates Posts: 198 Rating: (17)
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5/18/2008 9:37 AM	Rate (0)
oziboy Posts: 2 Rating: (0)	Ates in generally we use 13 bit cards which is 2^13 = 8192 but there are also 14 bit cards = 2^14 = 16384 and 2^15 = 32768 which is the last point of card .. 27648 - 16384 = 11264 16384 / 11264 = 1.454545 .45 is for overflows .. so in the end i dont know :) why is a cd 65 min ? because the one who invented it likes mozarts x senphony which is 65 min :) Yes I too asked this question to many of the Instructors and Siemns trainers,But could not got satisfactoy answer.Is any body can give some expination or some data sheets to ead and understand will help me lot
oziboy Posts: 2 Rating: (0)
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5/18/2008 11:17 AM	Rate (7)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 11/30/2023 Posts: 12179 Rating: (2635)	Hello Pandiani; I can understand your question, although for practical purposes it matters more to know how to use the standard limits than to wonder why? In any case, let's look at the following attachment, from the Siemens S7-300 module data manual. It showsthe representation of unipolar 0-20/4-20 mA signals for analog modules in Siemens' S7-300world. First, notice that the full scale range represents 85% of the full + overshoot ranges, on this scale. Or if you prefer, 27468 *32511 = 0.15 (approximately, see below).This 15% overshoot area(both overshoot and undershoot, please validate for yourself) allows room for interpretation by the user. Second, look at the hex equivalents on the decimal numbers used as range limits. They all end in xx00 or xxFF, which makes evaluation of the boundary very easy to program, no? So it looks like the numeric approximations were linked to the pivotal values of these numbers in hex. Anyway, outside of a direct answer from Siemens personnel who could have actually worked on these units, this is the best inferrence I have been able to find. I have worked with these assumptions for a while now, and they seem to cover most requirements (for my needs anyway). If someone has a reference to any other explanation, I personnaly would be very interested in reading about it. Regards, Daniel Chartier Attachment S7_analogRep_Current.jpg (6351 Downloads)

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This contribution was helpful to 18 thankful Users Berg how come SolutionFinder Ayman Elotaify Akachi Tranhieu0983 uptomyeyes S7 AUTOMAN KIRAN_DABHI caragan htet r_p_williams akup2017 Med_selmi socrames Jozao Shebo Jenda

5/30/2010 7:45 PM	Rate (0)
metwally Posts: 6 Rating: (0)	thank you
metwally Posts: 6 Rating: (0)
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4/6/2014 6:09 AM	Rate (0)
Tranhieu0983 Bronze Member Joined: 9/24/2010 Last visit: 11/24/2023 Posts: 118 Rating: (10)	So great :), i always wonder why siemens choose 27648, but now when i read this topic that make me understand a lot of. Thank again
	Mechatronic Center Website: www.plcvietnam.com.vn Email : tvhieu.plc@gmail.com
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This contribution was helpful to 1 thankful Users metwally mustafa

5/19/2014 2:29 PM	Rate (0)
Ayman Elotaify Platinum Expert Joined: 5/28/2008 Last visit: 11/29/2023 Posts: 4485 Rating: (834)	dchartier ............... First, notice that the full scale range represents 85% of the full + overshoot ranges, on this scale. Or if you prefer,2746832511 = 0.15 (approximately, see below).This 15% overshoot area(both overshoot and undershoot, please validate for yourself) allows room for interpretation by the user. ............... Hello, Just small correction for Daniel Chartier's answer in the max. count value. It is "27648*" And may be this thread explains or add some info. How 27648 Analaog Maximum Value ? Hope this helps.
	Last edited by: Ayman Elotaify at: 5/19/2014 3:19 PM Last edited by: Ayman Elotaify at: 5/19/2014 3:19 PM Last edited by: Ayman Elotaify at: 5/19/2014 3:18 PM Ayman Elotaify
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5/19/2014 2:38 PM
Madhava Silver Member Joined: 11/26/2011 Last visit: 6/29/2023 Posts: 508 Rating: (21)	Here you find more explanation Attachment AI.pdf (3327 Downloads)

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5/28/2014 9:16 AM	Rate (0)
MHasan Posts: 63 Rating: (4)	the replies which every send are near to conclusion, but i would liketo add one more thing Its not only numbers but also the internal circuitry in which different combination of chips are used forces the manufacturer to select best suitable range.
MHasan Posts: 63 Rating: (4)
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5/30/2014 8:35 PM
KIRAN_DABHI Posts: 60 Rating: (8)	THANKS FOR POST. THIS CALCULATION IS BASED ON RESOLUTION.
KIRAN_DABHI Posts: 60 Rating: (8)
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