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6
How Motion Works
EZMotion offers six different motion object types. These six types are Jogs, Home, Indexes, Gearing, Camming, and Torque
Mode. All motion objects run on what is called a Profile. Only one motion object can run on a Profile at a time. For applications
that need to run multiple motion objects simultaneously, EZMotion has two different Profiles. This will be discussed further in
the Summing Multiple Profiles on page 45 subsection.
This section will concentrate on how the different motion objects work, and not on how they are configured using PowerTools
Pro. For more information on how to configure the motion objects in PowerTools Pro, see Configuring an Application on
page 47.
6.1
Jog
Jog is a motion object that has Acceleration, Velocity, and Deceleration, but no dedicated distance. The user pressing a push
button or foot pedal often controls jog motion. When the user presses the Jog button, the jog accelerates up to the jog velocity
and continues to run at that velocity until the user releases the Jog button. When the user releases the Jog button, the jog
decelerates from the Jog Velocity back down to zero velocity (stopped).
Figure 35shows an example of a Jog profile.
Jog.PlusActivate
Figure 35:
The distance traveled by a Jog is entirely dependant on the duration that the Jog signal is held active. To accurately control the
distance the motor moves, an Index is the preferred motion object type.
6.2
Home
Home is a motion object that has Acceleration, Velocity, and Deceleration. A Home works by accelerating up to the specified
velocity until a reference signal activates. Once the reference signal activates, the motor either begins to decelerate to a stop
immediately (called Calculated Offset), or continues at the Home velocity and comes to a stop a specified distance from where
the reference signal activated (called Specified Offset).
The Home is typically used to define a reference position (or Home position) on a machine. This can be done in several
different ways depending on what type of Home Reference is used. The Home Reference determines what action or signal
defines the Home position. The three types of Home Reference supported by EZMotion are Marker, Sensor, and Sensor then
Marker. Following is a description of the three different Home types.
6.2.1
Home to Marker
Most motors used with the drive have an encoder mounted in the back end of the motor. This encoder is used to feed
positional data back to the drive or EZMotion for position control. Each encoder has a special signal called the Encoder Marker
Channel that activates once every revolution of the motor. EZMotion can use this Marker as a reference signal when executing
a Home.
The Marker provides an extremely accurate means of homing the system. EZMotion will detect a rising edge of the Encoder
Marker signal every revolution of the motor shaft. The Home routine begins by accelerating up to the Home Velocity. The
motor continues at the Home Velocity until the Encoder Marker activates. The motor then decelerates to a stop immediately, or
continues for a specified offset distance. Figures 36 and 37 show examples of the Home to Marker profile, with calculated
offset and with specified offset respectively.
EZMotion User/Programming Guide
Revision A8
Velocity
Jog Velocity
Jog Accel
Jog Profile Diagram
www.controltechniques.com
Jog Decel
Time
33
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