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Old March 7th, 2018, 03:22 PM   #16
Bullzi
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That is a good information i appreciate the effort.
this in case of min and max (lbs)
what if i want to convert volt to pound
so when i press on the scale it measure in volts over my analog input card.
will SCLP instruction help as well?
I think you may misunderstand how the Analog module works in a PLC system. It basically converts your analog signal (0-10V) to numbers via a Analog to Digital Converter. In your case those numbers are 0 to 31206. The PLC Processor uses those numbers only. It doesn't know what voltage is at the input, just the numbers that the input voltage represents.

The SCLP or Scale with Parameters is just a add on instruction for Ladder Programming or you can use SCP in Function Block Programming. In either case the instruction takes the A to D values (0 to 31206) and scales them to a "real world" value which in your case is 5 to 100 lbs. You can then use the "real world" numbers in your PLC program to do what ever you need.
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Old March 7th, 2018, 03:34 PM   #17
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In this case of a Compactlogix and a 1769-IF4, You ALSO have the option of asking the card to display in engineering units(ie, volts if you are running in 0-10V mode) instead of the 'raw' counts.
This is not true of all cards/plc/etc.

If you go into the module properties, configuration, You may change a channel from raw/proportional to one of the other options(which are documented in the manual for the 1769-IF4 manual)

But, as Bullzi mentioned, You could simply take the raw values and scale them to voltage just as easily using a scaling equation, a SCP Function Block, a compute instruction in ladder, etc.
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Old March 7th, 2018, 03:35 PM   #18
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Thanks guys
I really appreciate the effort
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Old March 7th, 2018, 05:13 PM   #19
Bullzi
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In this case of a Compactlogix and a 1769-IF4, You ALSO have the option of asking the card to display in engineering units(ie, volts if you are running in 0-10V mode) instead of the 'raw' counts.
Just to clarify what Darvik said. If you do use Engineering Units 0-10v will give you a value from 0-10000. So you will have to divide by 1000 to get actual volts. What he said is correct just the be aware that the value is a integer not a float like you might expect.
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