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Analog Output

10/5/2010 9:55 PM	Rate (0)
Andy Moods Posts: 33 Rating: (0)	Hi Guys You have been a great help thus far and i am hoping for a little bit more. I need to scale a % value to 4 to 20 mA output. i have used a Div and Mul block to first divide by 100 and then multiply into the value of 27648, but after that i am stuck. I have used a convert to convert the real value to a word, but it stops right at that point and the word has useless info and hence my stuff does not work as it is getting no output. Not sure if scale_x and norm_x are the right tools here. Can someone please help?!?
Andy Moods Posts: 33 Rating: (0)
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10/5/2010 10:35 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/15/2024 Posts: 15402 Rating: (2443)	Maybe it's just me, but it could be as simple as leave everything in the REAL world as follows: (AN_IN - 4.0) * (100.0/16.0) = Scaled_AN_IN (with range of 0.0 - 100.0 ) Offset the input -4.0, which makes it 0.0-16.0mA, so now we scale up 16.0 to 100.0. Leave everything as real until the end, then convert to integer with a ROUND or TRUNC Hope that is what you were after. ---- After reading again, perhaps I misunderstood. 4mA = 0 20mA = 27648 If that is correct, convert to 0-100 by 27648.0/100.0 * AN_IN which is precisely what you attempted. CONV the analog input in UINT to REAL, DIV by 100.0, MUL by 27648.0, save results to SCALED_AN_IN_REAL, CONV to UINT as SCALED_AN_IN_UINT Maybe that's what you were trying?
	Last edited by: huggy_d1 at: 10/5/2010 10:38 PM Added more information. science guy
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10/6/2010 10:09 AM	Rate (0)
Andy Moods Posts: 33 Rating: (0)	Hi i am looking for a solution for analog outputs and not A/I Thanks
Andy Moods Posts: 33 Rating: (0)
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10/6/2010 3:15 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/15/2024 Posts: 15402 Rating: (2443)	After reading again, I misunderstood. 4mA = 0 % = 0 output counts 20mA = 100 % = x-bit output counts See attached image for a working scaling for 0-20mA & 4-20mA. My S7-1200 AO module only does 14-bit math, and only does 0-20mA. To make it 4-20mA, you have to set 0.0% control signal to 4mA and 100.0% to 20mA. The values to plug-in are in the comments for the logic. This is working on my S7-1200 project as I was live on-line testing values and see accurate analog output signals based on the 0-100% control signals. It even has range checking and out of range correction (instead of leaving the old control signal set).. Attachment Analog_Output_Scaling.jpg (1086 Downloads)
	science guy
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10/7/2010 12:08 PM	Rate (0)
Denilson Pegaia Platinum Expert Joined: 9/23/2005 Last visit: 11/14/2024 Posts: 4352 Rating: (1452)	Hi, there is also a read to use block on /tf/WW/en/Posts/31698
	Denilson Pegaia Siemens Industry Sector Technical Support
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