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Chapter 4 Functional Overview
7344/7334 Hardware User Manual 4-2 ni.com
The DSP chip is a separate processor that operates independently from
the CPU but is closely synchronizedby an internalpacket-based command,
data, and messaging event structure. The 7344/7334 controllers are true
multiprocessing and multitasking embedded controllers.
The advanced architecture of the 7344/7334 controller enables advanced
motion features, such as enhanced PID functions. Refer to the FlexMotion
Software Reference Manual for more information on the features available
on the 7344/7334 controllers.
Trajectory Generators
The 7344/7334 controller trajectory generators calculate the instantaneous
position command that controls acceleration and velocity while it moves
the axis to its target position. This command is then sent to the PID servo
loop or stepper pulse generator, depending on how you configure the axis.
To implement infinite trajectory control, the 7344/7334 controller has
eight trajectory generators implemented in the DSP chip—two per axis.
Each generator calculates an instantaneous position each PID update
period. While simple point-to-point moves require only one trajectory
generator, two simultaneous generators are required for blended moves
and infinite trajectory control processing.
Analog Feedback
The 7344/7334 controller has an 8-channel multiplexed, 12-bit ADC. The
converted analog values are broadcast to both the DSP and CPU via a
dedicated internal high-speed serial bus. The multiplexer scan rate is
approximately 50 µs per enabled ADC channel. This provides the high
sampling rates required for feedback loop closure, joystick inputs, or
monitoring analog sensors. Four of these channels are intended for
calibration, leaving the other four available for analog feedback.
Flash Memory
Nonvolatile memory on the 7344/7334 controller is implemented with
flash ROM. This means that the 7344/7334 controller can electrically erase
and reprogram its own ROM. Since all the embedded firmware, including
the RTOS and DSP code, of the 7344/7334 is stored in flash memory, you
can upgrade the onboard firmware contents in the field for support and new
feature enhancement.