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Chapter 3
Hardware Overview
Functional Overview
This section provides an overview of motion control algorithms and the NI PXI/PCI-7340
controller.
Dual Processor Architecture
With the NI 7340 motion controller, you can perform up to four axes of simultaneous,
coordinated motion control in a preemptive, multitasking, real-time environment.
An advanced dual-processor architecture that uses a 32-bit CPU combined with a digital signal
processor (DSP) and custom FPGAs give the NI 7340 motion controller high-performance
capabilities. The FIFO bus interface and powerful function set provide high-speed
communications while off-loading complex motion functions from the host PC for optimized
system performance.
The NI 7340 motion controller uses the DSP for all closed-loop control, including position
tracking, PID control closed-loop computation, and motion trajectory generation. The DSP chip
is supported by custom FPGAs that perform the high-speed encoder interfacing, position capture
and breakpoint functions, motion I/O processing, and stepper pulse generation for hard real-time
functionality.
The embedded CPU runs a multitasking, real-time operating system and handles host
communications, command processing, multi-axis interpolation, error handling,
general-purpose digital I/O, and overall motion system integration functions.
Embedded Real-Time Operating System (RTOS)
The embedded firmware is based on an embedded RTOS kernel and provides optimum system
performance in varying motion applications. Motion tasks are prioritized. Task execution order
depends on the priority of each task, the state of the entire motion system, I/O or other system
events, and the real-time clock.
The DSP chip is a separate processor that operates independently from the CPU but is closely
synchronized. The NI 7340 motion controller is a true multiprocessing and multitasking
embedded controller.
The advanced architecture of the NI 7340 motion controller enables advanced motion features,
such as enhanced PID functions. Refer to the NI-Motion Help for more information about the
features available on the NI 7340 motion controller.
Trajectory Generators
The NI 7340 motion controller trajectory generators calculate the instantaneous position
command that controls acceleration and velocity while it moves the axis to its target position.
Depending on how you configure the axis, this command is then sent to the PID servo loop or
stepper pulse generator.
3-4 | ni.com
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