Integrated Motion on the EtherNet/IP Network
Chapter 1
Rockwell Automation Publication MOTION-RM003I-EN-P - February 2018
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A feedback device for this configuration is optional. In the absence of a feedback
device, actual velocity can be estimated by the drive and returned to the controller.
Closed Loop Velocity Control Method
A motor control device configured for closed loop velocity control is traditionally
referred to as velocity loop drive or velocity servo drive. A closed loop velocity
control drive implies an inner torque/current control loop and therefore is
sometimes referred to as a vector drive.
A feedback device for the velocity loop drive configuration is optional. You can
achieve tighter speed regulation when using a feedback device, particularly at low
speed. When the feedback device is included it may be used to return actual
position, velocity, and acceleration data to the controller using the cyclic data
connection. When the feedback device is not included, only estimated velocity can
typically be returned to the controller.
In addition to Command Velocity, the controller can also pass Command
Acceleration for the purposes of forward control.
Acceleration Control Method
While not a mainstream control mode in the industry nor mentioned in the IEC
standard, the acceleration control mode is included here to complete the dynamic
progression from velocity control to torque control and because the Motion
Control Axis Object can support an Acceleration Command, potentially derived
from the controller's motion planner. In the acceleration control mode, the
application control program and motion planner provide acceleration set-point
values to the CIP Motion device using the cyclic data connection. The drive
converts the acceleration set-point into a torque command using the estimated