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Scale Analogue Output

Created by: S7 Smuck at: 7/15/2021 3:47 PM (9 Replies)

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7/15/2021 3:47 PM	Rate (0)
S7 Smuck Advanced Member Joined: 8/3/2016 Last visit: 4/5/2024 Posts: 64 Rating: (0)	Hello all, I am having a real nightmare trying to scale an AQ on a Logo. I use the 1200 range regularly but for this project i thought I’d use a logo due to the simplicity…. Or so I thought! Background I have a logo collecting modbus data from a power meter and I need to scale the kw value from the power meter to a 0-10 or 4-20mA signal Two issues I have: The power meter data is float data type made up from two 16bit word registers, how can I read this value in my logo? Expected value is -2000.0 to 2000.0 kW Once I have this value how do I scale the output as below 0-10V -2000.0 – 2000.0 0r 4-20mA -2000.0 – 2000.0 In the 1200 it’s a relatively easy task but in the logo I’m getting completely lost or missing something! Any help appreciated!
	Last edited by: S7 Smuck at: 07/15/2021 16:02:11 Last edited by: S7 Smuck at: 07/15/2021 16:04:25
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7/15/2021 3:50 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 12/7/2024 Posts: 34363 Rating: (4281)	S7 Smuck In the 1200 it’s a relatively easy task but in the logo I’m getting complete lost or missing something! Any help appreciated! The LOGO! programmer sees it so. In LOGO! very easy, but in S7-1200 ...

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7/15/2021 4:01 PM	Rate (0)
S7 Smuck Advanced Member Joined: 8/3/2016 Last visit: 4/5/2024 Posts: 64 Rating: (0)	Great! Any tips appreciated! i'm seriously looking to ditch the LOGO and bring a 1211C in tomorrow! Cheers M

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This contribution was helpful to 1 thankful Users ixo65

7/15/2021 4:04 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 12/7/2024 Posts: 34363 Rating: (4281)	See the screenshot. The first amplifier is only for testing with the values -2000 to 2000. The second amplifier ist that what you need. Sensortype: None Gain = 0.25 Offset = 500 By the AQ for 4-20 mA must then make the setting for 4-20mA.

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7/15/2021 4:05 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 12/7/2024 Posts: 34363 Rating: (4281)	S7 Smuck Great! Any tips appreciated! i'm seriously looking to ditch the LOGO and bring a 1211C in tomorrow! Cheers M Oh ... Don't you understand fun?

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7/15/2021 4:09 PM	Rate (0)
S7 Smuck Advanced Member Joined: 8/3/2016 Last visit: 4/5/2024 Posts: 64 Rating: (0)	Of course but this is nuts! How do you get a gain of 0.25 and offset off 500 to equal a scale of -2000 - 2000? Cheers M

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7/15/2021 4:17 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 12/7/2024 Posts: 34363 Rating: (4281)	An analog output by LOGO! is controlled with 0-1000 units. Then only the output has to be set to its range, either 0-10V / 0-20mA or 4-20mA. -2000 to 2000 multiplied by a gain of 0.25 results in -500 to 500. The offset of 500 then corrects this range to 0-1000.

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7/15/2021 4:35 PM	Rate (0)
S7 Smuck Advanced Member Joined: 8/3/2016 Last visit: 4/5/2024 Posts: 64 Rating: (0)	Thank you for the info. The project here is more complex than I anticipated, i have to do some additional math and write the data to a different slave address also. I'll bring a 1211 with me tomorrow and save this logo for some of the logic panels we supply. Cheers M

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7/15/2021 4:40 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 12/7/2024 Posts: 34363 Rating: (4281)	Since I don't know your project, of course I don't know what you have to calculate. But the LOGO! even if only to a limited extent. And the LOGO! can communicate with an S7-1200 or S7-1500 also.

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7/16/2021 9:31 AM	Rate (0)
S7 Smuck Advanced Member Joined: 8/3/2016 Last visit: 4/5/2024 Posts: 64 Rating: (0)	HI, Yeah i'm sure it will do it but I have limited time on this one so i'll stick with what i know on the 1200. the Logo is a great product but i just couldnt get my head around that scalling yesterday from modbus to AQ. I'll use it on another project when I have more time :-) Thanks for teh response. Cheers M

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