Rockwell Automation 2711-ND3 PanelBuilder v2.60 Software User Manual - Manual (Page 156)

10–4 Creating Data Entry Controls
Publication 2711-6.0
Data Entry Scaling
Data entered by an operator can be scaled from engineering units
such as gallons or pounds per square inch to machine control values.
Terminal values are scaled using the formula:
y = mx + b
y = scaled value (entered by operator)
m = scale (multiplier)
x = controller value
b = offset
To calculate value (x) stored at the controller address, use:
x =
y - b
m
=
Entered Value - Offset
Scale
The scale and offset values are entered in the Tag Editor. Scaled
values affect the controller value as follows:
•
Scale (m) value >1 generates an x value smaller than y-b.
•
Scale (m) value <1 generates an x value larger than y–b.
Example: Scaling a Data Entry Variable
The operator enters 30 (pounds) for (y). The offset (b) value is 2.
The scale (m) value is .01.
x =
y - b
m
=
30 - 2
.01
= 2800
The terminal provides a controller match value of 2,800 for a weigh
scale transducer:
G
Value from
Weigh Scale= 2,800
Operator Inputs
Weight of 30 Pounds
PanelView Terminal
Scales Value to 2,800
for Match Code
Weigh Scale Value (2,800)
Matches Input Value (2,800)
Package is Accepted
➂
➁
➃
➀
The value displayed in a numeric entry object may or may not be
scaled. The displayed value may be assigned a tag name independent
of the value written to the controller (write tag) address.