adccommunitymod (AutomationDirect) asked a question.
Scaling Analog Inputs
Created Date: May 12,2005
Created By: carane
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Hi, i would like to know how to scal analogic inputs in a DL-205, which directions i have to use??? Thanks
Created Date: May 12,2005
Created by: carane
Hi, i would like to know how to scal analogic inputs in a DL-205, which directions i have to use???
Thanks
Created Date: May 12,2005
Created by: rex2802
H-L
Units = A -------
4095
H = High limit of the engineering unit range
L = Low limit of the engineering unit range
A = Analog value (0-4095)
Created Date: May 12,2005
Created by: rex2802
Sorry it didn't post the way I typed it.
H-L/4095*A
Created Date: May 13,2005
Created by: Tom Jenkins
For any unit conversion on any PLC you can use four function math with the following,which asumes integer math:
DataOffset = Data in input register at 4 mA or zero analog signal of whatever range - for example 0 VDC on a 0-10 VDC transmitter)
DataSPan = Data at 20 mA - Data @ 4 mA
FACTOR = arbitrary factor (multiple of 10)needed to get proper resolution and accuracy
EU = Engineering Units x FACTOR
EUOffset = Engineering Units @ 4 mA x FACTOR
EUSpan = (Engineering Units @ 20 mA -Engineering Units @ 4 mA) x FACTOR
DATA = Actual data reading in input register
EU = ((EUSpan x (DATA - DataOffset))/DataSpan) + EUOffset
ProcessValue = EU / FACTOR
For Example, 0-60 psig from 4-20 mA with resolution of 0.1 psig:
FACTOR = 10
Data @ 4 mA = 6240
Data @ 20 mA = 31208
DataOffset = 6240
DataSpan = 31208 - 6240 = 24968
EUOffset = 0 x 10 = 0
EUSpan = (60 - 0) x 10 = 600
DATA = 18975
EU = ((600 x (18975 - 6240)) / 24968) + 0 = 306
Process Value = 306 / 10 = 30.6 psig
You would use the normal math functions to accomplish this. Just make sure you do your diovides AFTER the multiplies.