Why use a Measurement Function-Block?

The Measurement FB:

measures between geometry, but in the Mechanism-Editor.
the measurement dimension is a 'driven dimension'
it is a 'dynamic' measurement - it continually updates as you cycle the mechanism.

The Dimension in the graphic area may be the:

Length of a Line
Distance between: two Points, a Line and a Point, two parallel Lines
Angle between: two Points, two Lines, three Points.

The Function-Block:

has two output-connectors when you measure between two Points
has one output-connector when you measure between all other sketch-elements.
each output-connector gives all motion-derivatives of linear and angular dimensions.

Measurement FB

Add Mearurement Fb

Kinematics FB toolbar > Measurement FB [right of Graphic-Area >>]


Add menu > Add Measurement FB


1.Click the Measurement FB in the Kinematics Function-Block Toolbar.
2.Click the sketch-element, or sketch-elements, between which you want to measure.
3.Click the graphic-area to complete the command.

The Measurement FB and the measurement dimension show in the graphic-area.


There are three different ways to use the motion-values at the output-connector of a Measurement FB:

1.Use a Graph FB to plot Linear or Angular Position, Velocity and Acceleration of the Measurement.
2.Use the Measurement's motion-values at the input and independent variable of a different FB, rather than a Linear-Motion FB.

For example:

Use the Measurement's motion-values as the independent variable of a Motion-Dimension FB, for a Rocker or Slider.

The Rocker or Slider will move with the motion as given by the output from the Measurement FB.

Note: Options 2: a message in the Feedback area: '1 Mechanism dependencies detected'. You should rebuild the model when the number of dependencies becomes more than 1 if the data is critical, before you save Cam-Coordinates, for example.

Top-Tip - 1

You can click the X-axis or Y-axis from which to measure the position of a Point or Line,and also the angle of a Line.

Top-Tip - 2

To plot the position, velocity and acceleration of a Measurement in the same graph:

1.Drag a wire from the same output-connector of the Measurement FB three times to three different input-connectors on a Graph FB.
2.Use the Y–axis display options in the Graph dialog-box to display all motion derivatives.

Top-Tip - 3

If you only want to know the length of a Line then CTRL+Click the Line to show the Element-Properties dialog-box for the Line.

See Also:

Connecting FBs

Measurement FB - more details

How to Add a Measurement FB

Add Mearurement Fb

STEP 1: Add menu > Add Measurement FB
Kinematic FB toolbar > Add Measurement FB
Measrement FB between two Points

Measrement FB between two Points

STEP 2: Click sketch-elements in the graphic-area
STEP 3: Click in the graphic-area to place the Measurement FB.

The Measurement FB1s-red is near to the dimension4s. You can drag the FB to a more convenient location.

In this example: The dimension4s is between two Points3s2s

The Measurement FB has two output-connectors when it measures between two Points

The Measurement FB has one output-connector when you measure between other sketch-elements.

See details below for motion-values available from the output-connectors.

tog_minusLinear Distance

Length or Radius
Distance between Two Points
Perpendicular Distance between a Point and a Line



Measurement Dimension


Line or CAD-Line.

Circle or Arc.

Length: The length of the Line!

Radius: The radius of the circle or arc.


Two Parallel Lines.



It is often difficult to measure the distance between two parallel lines.

The Measurement FB will often return the angle between the lines as 0º, 360º or 180º.

Measure from one of the Lines and a Point at the end of one of the Lines.

See Also: Angle Measurement between Two Lines, and Distance between Line and Point.


Two Points

Distance between two Points.

The Measurement FB has two output-connectors:

Top output-connector: gives the gap, the rate-of-change of the dimension and the second rate-of-change of the dimension
Bottom output-connector: gives the angle, angular velocity and angular acceleration between the Points.


Point and a Line

Perpendicular Distance between a Line and a Point.

Select the Point, then the Line.

You many need to add a Line to a Part in the Part-Editor.

To measure a 'Horizontal Distance' or a 'Vertical Distance' you can select the X-axis or Y-axis as a Line.

tog_minusAngle between Three Points

My work-around when two Points are at one Point, but I want to add a measurement with the Point at the apex of an angle.

1.Edit the Part and add a 'Free' Line so that its start-Point is near to the coincident Points.
2.Add the Measurement: Three Points with the Points at each end of the Line, plus another Point.

When you do this, the angle is not yet giving the angle you actually want.

3.Edit the Part to make one of the Points at the end of the Line to be coincident with the Point you want to be the apex of the angle.

Now, the angle is the angle you want.

Measurement: Angle between Three Points

In the graphic-area:

1.Click a Point '1'.

Point '1' is the 'apex' of the angle.

2.Click Point '2'
3.Click Point '3'.

The Measurement FB displays the counter-clockwise angle from Point '2' to Point '3'.



Measurement Dimension


Three Points

1.Click 'Apex' Point 1s-red
2.Click Point 2s
3.Click Point 3s

Internal Angle

Angle is from 2s to 3s in a Counter-Clockwise direction.


Three Points

1.Click 'Apex' Point 1s-red
2.Click Point 2s
3.Click Point 3s

External Angle

Angle is from 2s to 3s in a Counter-Clockwise direction.

tog_minusAngle between Two Lines


Add Measurement FB :

two Lines

Eight[8] possible angles


After you select the two Lines, and before you click in the graphic-area to place the Measurement FB and angle dimension, you can display one of eight possible angles.

Move your mouse-pointer around the apex of the two lines:

Counter-clockwise : dimension < 180° , namely, the Acute, Obtuse, Supplementary and Vertical angles,

Clockwise : dimension > 180° : namely, the 'reflex angles' to those < 180°.

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd