2.16.2.1.17 XY chart element

This element shows the relation of two numeric variables in an X/Y diagram, featuring a 'track' which shows the recent history of the values with a configurable depth. The update rate, the diagram scaling and much more is configurable with this screen element.

The X/Y chart display may be scaled to an almost arbitrary size, however the following limitations apply:

• The annotation labels which reflect the actual display settings are not scaled with the display element. If the element is very small, the labels may overlap and become unreadable.
• Resizing the X/Y chart display element is only possible in certain steps, the grid behind the curve is always made up of a number pixels in one dimension which is divisible by the configured number of diagram divisions without remainder. The screen editor software knows about this, snaps the size of the element to the next (smaller) valid size after you release the mouse button.

The attributes listed below may be configured to customize a display element of this type:

• MessageID(x) message ID (y): The message IDs of the parameters to show.
• Label: The annotation label displayed above the X/Y chart.
• Font: Font contains two options:
  • Font: The font attribute applies to the text shown in the parameter field itself. The label text is shown with the standard ("plain") font size for all font selections except the smallest one. In the latter case the label is drawn using this small font size, too.
  • Color: The color of the label displayed above the X/Y chart. Colors may be specified by using a hexadecimal RGB notation. You may click to the color example field in order to open a color chooser dialog and select the color from there.
• Chart settings
  • Divisions: The number of divisions shown in the diagram for both directions. You may enter arbitrary values here, but to achieve some readability, you are encouraged to us common values like 2 ('hair cross'), 4 or 10.
  • Interval: The update time interval for the display in seconds. 0.1 means to add every 100msec a new value to the display and remove the oldest value from the buffer at the same time.
  • Buffer size: The display maintains a "first in first out" buffer of a size defined with this parameter. The buffer provides a short time memory the display shows as a trace of past values. Values in the range 100-300 are a good choice, larger values may slow down the client application. Please note, that the buffer gets cleared when the window is closed.
• Origin and scale
  • x origin y origin: The origin values refer to the center of the diagram. Using an even number of divisions helps to identify the diagram center as the cross point of the middle grid lines
  • x scale y scale: The scale values are per division. with x origin = 0.0 and x scale = 1.0 an x value of 1.0 gets displayed one division right of the diagram center.
• Monitor limits: With this checked, the display monitors the actual X/Y values to be within the limits defined below. The limit values are shown as a dark red rectangle. When the while the actual X/Y values exceed the limits, the diagram background becomes red.
  • min x value, max x value, min y value and max y value: The limit values for X and Y to be checked.