ADLINK Technology cPCI-8168, User Manual

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40 Operation Theory
4.1.2 Pulse type motion control Interface
The second interface of motion and motor control is pulse train
type. The counts of pulses show how many steps a motor rotates
and the frequency of pulses show how fast a motor runs. The time
duration of frequency changes represents the acceleration rate of
a motor. This interface is easier to use than an analog type motion
controller when controlling position applications of a servo or step-
per motor, allowing motion and motor control to be separated eas-
ily.
Both of these interfaces require manual gain tunning. For analog
type position controllers, the control loops are built inside and
users must tune the gain from the controller. For pulse type posi-
tion controller, the control loops are built outside on the motor driv-
ers and users must tune the gains on the drivers.
For more than one axes’ operation, motion control seems more
important than motor control. In industial applications, reliability is
a very important factor. Motor driver vendors make good perfor-
mance products and motion controller vendors make powerful
controllers and offer a variety of motion software. Integrated two
products make our machine go into perfect.
4.1.3 Network type motion control Interface
The network type motion controller is the newest control interface.
With this interface the command between motor driver and motion
controller is not an analog or a pulse signal. Instead, the command
is a network packet containing position and motor information.
This type of controller is more digitized and packetized making it
more reliable than the other interfaces. Since a motion controller
must be real-time, the network must have real-time capacity
around a cycle time below 1 mini-second. This means that a non-
commercial network can do the job. It must have a specific net-
work like Mitsubishi SSCNET. The network may have opto-fiber
type to increase communication reliability.