National Instruments NI-Motion - Manual (Page 23)

Chapter 1 Introduction to NI-Motion
© National Instruments Corporation 1-9 NI-Motion User Manual
Figure 1-7. NI SoftMotion Controller Functional Architecture for CANopen
In this configuration, the I/O and the control loop execute on the CANopen
drive. The NI SoftMotion Controller uses an NI-CAN device to
communicate to the CAN bus.
NI SoftMotion Controller Communication Watchdog
The supervisory control in the NI SoftMotion Controller continuously
monitors all communication with the drives connected to the host. If any
drive fails to update its data in the host loop update period, the axis
corresponding to that drive is disabled and the communication watchdog
status bit, which is returned by the Read Per Axis Status function, is set to
TRUE. Similarly, all drives connected to the NI SoftMotion Controller are
configured to go into a fault state if the data from the
NI SoftMotion Controller is not updated every host loop update period on
the drives.
The communication watchdog functionality ensures that the NI SoftMotion
Controller operates in real time.
Tip To get an axis or axes out of the communication watchdog state, reset the
NI SoftMotion Controller.
Trajectory
Generation
Supervisory
Control
I/O**
CAN Bus
CANopen Drive
NI SoftMotion Controller
on Host Device*
*Host device is a PC or PXI chassis running the
LabVIEW Real-Time Module
**I/O includes encoder implementation
Control
Loop
Spline
Engine