Analog Graph - Scalling question

I haven't needed it either yet. And the manual is somewhat unclear what these K and N values actually do or how to calculate them. Here is a little explanation.

In the equation Y = KX + N, K is the slope or rate of change (how much Y changes for each unit increase in X), and N is the Y-intercept or the vertical shift (the value of Y when X is zero). Together, K and N determine the specific linear relationship between the variables X and Y, with K dictating the steepness of the line and N controlling its vertical position on a graph. Understanding K (Slope/Rate of Change)

• Definition: K is the constant of variation or the slope.
• Meaning: It tells you how much the dependent variable (Y) changes in response to a one-unit change in the independent variable (X).
• On a Graph: K represents the slope of the line. A positive K indicates the line rises from left to right, while a negative K means it falls.
• Calculating K: If you know a point (X, Y) on the line (and N=0), you can calculate K by dividing Y by X (Y/X = K).

Understanding N (Y-intercept/Vertical Shift)

• Definition: N is the y-intercept.
• Meaning: It's the value of Y when X equals zero, meaning it's the point where the line crosses the y-axis.
• On a Graph: N determines the starting point or the vertical positioning of the line.
• Direct vs. Linear Proportion: In a strictly proportional relationship (Y=KX), the line must pass through the origin (0,0), meaning N would be 0. The presence of N in Y=KX+N makes the relationship a linear one, not a directly proportional one.
  
  

Example

Temperature probe: Analog Log-scale.bos
Raw: 0 – 1023 counts ↔ scale to: 0 – 100 °C
K = (100 – 0) / (1023 – 0) = 0.0977 (°C per raw count)
N = 0 – 0.0977 × 0 = 0
So if your sensor is sending out values temperature values as0-1023 then the analog log will scale its value to 0-100 range.

If instead the sensor is 0.1 V → 0 °C, 0.4 V → 100 °C, and the PLC turns 0.1 V into 512 counts, 0.4 V into 2048 counts:
K = (100 – 0) / (2048 – 512) = 0.0769
N = 0 – 0.0769 × 512 = –39.4 (≈ –39)

Thanks a lot Jürgen, very useful !

Not obvious at all I must say... It would have been really helpful to find something in the doc. At least there is something really understandable here now.

I have a silly question: In analog graphs, it is possible to scale data.Since I have never needed to do this, I haven't looked into To answer a scaling question for an analog  monkey type  graph, you need to identify the minimum and maximum values of the data you want to plot and choose a suitable scale for each axis that fits the graph paper's dimensions, ensures clear visibility, and clearly labels the units. The chosen scale should make the most relevant parts of the data visible and allow for easy comparison by using consistent increments My values seem to be a little off. My Fluke meters are usually showing around 35A on L2 and L3 while my controller is showing 39A.