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To Move a Real Number with 8 decimal points

Created by: ssmanku1699 at: 12/21/2013 5:10 AM (8 Replies)

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12/21/2013 5:10 AM	Rate (0)
ssmanku1699 Experienced Member Joined: 8/10/2009 Last visit: 1/24/2023 Posts: 166 Rating: (2)	Dear ALL , I need to move a fixed real time value with 8 decimal points in a real Tag like MD0. The issue is :- When I am trying to use MOVE BLOCK it is rounding up the number automatically . But in my application , I need 100 % accuracy so need to move real number with 8 decimal points fully.. How can I achieve it ? Thanks Sarabjot Singh Manku

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12/21/2013 6:48 AM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 1/27/2023 Posts: 13080 Rating: (2121)	ssmanku1699 Dear ALL , I need to move a fixed real time value with 8 decimal points in a real Tag like MD0. The issue is :- When I am trying to use MOVE BLOCK it is rounding up the number automatically . But in my application , I need 100 % accuracy so need to move real number with 8 decimal points fully.. How can I achieve it ? Thanks Sarabjot Singh Manku To copy a tag from one real number to another real number, just use the move instruction. If you want to convert it to an integer with 8 implied decimals, you will need a DINT and a MUL instruction as well as a CONV instruction.
	science guy
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12/22/2013 12:21 PM	Rate (0)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 1/18/2023 Posts: 1496 Rating: (217)	ssmanku1699 Dear ALL , I need to move a fixed real time value with 8 decimal points in a real Tag like MD0. The issue is :- When I am trying to use MOVE BLOCK it is rounding up the number automatically . But in my application , I need 100 % accuracy so need to move real number with 8 decimal points fully.. How can I achieve it ? Thanks Sarabjot Singh Manku Hello ssmanku1699, What is the range between your number lies?? Also can you please explain in the MOVE instruction what is the data type which you are using at the output end??
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12/26/2013 5:58 AM	Rate (0)
ssmanku1699 Experienced Member Joined: 8/10/2009 Last visit: 1/24/2023 Posts: 166 Rating: (2)	Dear Ganesh , For example , Let us say , I want to move the real number / Float value like 37.12345678 to MD0 with Move Instruction and MD0 is a real variable . But at the time of entering this number even at the starting end of MOVE instruction it is not taking as it is . It is rounding it to 37.12346 from 37.12345678 . Thats my issue. I want to move it fully like 37.12345678. Even tried to use DB at both the ends but of no use. Please help if you have faced such type of situation and resolved the same. Thanks Sarabjot Singh Manku

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12/26/2013 6:13 AM	Rate (0)
ssmanku1699 Experienced Member Joined: 8/10/2009 Last visit: 1/24/2023 Posts: 166 Rating: (2)	Dear Huggy D1 , I really dont understand your solution. Can you please elaborate ? I want to move a real number like 37.12345678 to an real Memory variable like MD0 . but while feeding the real value at the input end , ie at entering itself it is rounding up to 37.12346. Thanks Sarabjot Singh Manku

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12/26/2013 8:12 AM	Rate (0)
@shish Bronze Member Joined: 9/16/2011 Last visit: 9/10/2022 Posts: 291 Rating: (5)	Dear Mr. Manku, Can you pls tell me the value is the fixed value or coming from a transducer or transmitter
	Reg, @shish --- If satisfied with reply, Rate it ! If problem solved, hit THANK !
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12/26/2013 8:19 AM	Rate (0)
ssmanku1699 Experienced Member Joined: 8/10/2009 Last visit: 1/24/2023 Posts: 166 Rating: (2)	Dear Ashish , Its a Fixed Value Thanks Sarabjot Singh Manku

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12/29/2013 1:24 PM	Rate (0)
uel123 Gold Member Joined: 1/29/2006 Last visit: 1/26/2023 Posts: 431 Rating: (60)	Hi, ssmanku1699! It is a problem of resolution. Normal float format is 32 bit long, and such a number, as you are proposing (37.12345678) can not be represented with such high resolution in 32 bit format. In that special case, you should use double float format, which is 64 bit wide. Have fun! uel123.

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12/29/2013 1:37 PM	Rate (0)
Navnag Platinum Member Joined: 11/21/2007 Last visit: 1/21/2023 Posts: 2321 Rating: (302)	ssmanku1699 Dear Huggy D1 , I really dont understand your solution. Can you please elaborate ? I want to move a real number like 37.12345678 to an real Memory variable like MD0 . but while feeding the real value at the input end , ie at entering itself it is rounding up to 37.12346. Thanks Sarabjot Singh Manku Hello What type of calculation are you performing ?In Practice Rounding the value to5 digits instead of8 digits ( Total 7 digits instead of 10 digits )would result in an inacurracy of < 10^-7% which should be too small and can be ignored for most industrial applications. ( Unless of course you are calculating a trajectoryof a spacecraft to Mars ) Still if you feel that you really need this accuracy, you can use 64bit floating point numbers, although these are not easy to use in calculations inside S7 PLCs ) You can check outdchartier's comments in my previous post inUsing Double FLoat in S7 Cheers Navnag
	Last edited by: Navnag at: 12/29/2013 1:48 PM Last edited by: Navnag at: 12/29/2013 1:43 PM There is no such thing as the last bug in a program There are no stubborn bugs, There are only stubborn Debuggers.
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