Chapter 1 Introduction to NI-Motion
© National Instruments Corporation 1-3 NI-Motion User Manual
The controller CPU is a 32-bit micro-controller running an embedded real
time, multitasking operating system. This CPU offers the performance and
determinism needed to solve most complex motion applications. The CPU
performs command execution, host synchronization, I/O reaction, and
system supervision.
The DSP has the primary responsibility of fast closed-loop control with
simultaneous position, velocity, and trajectory maintenance on multiple
axes. The DSP also closes the position and velocity loops, and directly
commands the torque to the drive or amplifier.
Motion I/O occurs in hardware on an FPGA and consists of
limit/home switch detection, position breakpoint, and high-speed capture.
This ensures very low latencies in the range of hundreds of nanoseconds
for breakpoints and high-speed captures. Refer to Chapter 12,
Synchronization, for information about breakpoints and high-speed
capture.
The motion controller processor is monitored by a watchdog timer, which
is hardware that can be used to automatically detect software anomalies and
reset the processor if any occur. The watchdog timer checks for proper
processor operation. If the firmware on the motion controller is unable to
process functions within 62 ms, the watchdog timer resets the motion
controller and disallows further communications until you explicitly reset
the motion controller. This ensures the real-time operation of the motion
control system. The following functions may take longer than 62 ms to
process.
• Save Defaults
• Reset Defaults
• Enable Auto Start
• Object Memory Management
• Clear Buffer
• End Storage
These functions are marked as non-real-time functions. Refer to the
NI-Motion Function Help or the NI-Motion VI Help for more information.