Performance Motion Devices PR8358120, Руководство пользователя

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Operation
52
Prodigy/CME PC/104 User’s Guide
2
much longer, up to several 100 mSec. Read speed is the same as for other Memory resources, and takes just a few
nanoseconds. As for the dual-ported RAM, byte-size memory operations are not supported by the non-volatile
memory. The smallest memory unit that can be accessed is 16 bits.
The non-volatile memory can be rewritten a limited number of times. The worst case write limit cycle is 100,000 times
for a given memory address, but in typical operation, the limit is much higher. As a general guideline, to avoid erase/
write cycle limit problems, the non-volatile RAM should not be used for general purpose scratch RAM, and should
only be used to store permanent or semi-permanent parameters.
For complete information on the format and function of these, and other PRP actions, refer to the Prodigy/CME
Programmer’s Reference .
2.7 Signal Processing and Hardware
Functions
These functions are implemented in hardware and are not directly user-programmable. The following sections are
organized into related groups of signals, and provide information which may be helpful when connecting the motion
system.
2.7.1 Home, AxisIn, AxisOut, Limits, Hall Sensors
These signals are conditioned by the card, and then input or output directly to the Magellan Motion Processor. The
Magellan Motion Processor User’s Guide explains the functions provided in connection with these various signals. Most of
the signals are optional, and are connected depending on the nature of the application.
These signals are named
Home1-4, AxisIn1-4, AxisOut1-4, PosLim1-4
(positive direction limit input),
NegLim1-4
(negative
direction limit input), and Hall1A-4C (12 signals in all).
2.7.1.1 Connections & associated signals
These signals are single-ended digital inputs to the card, with the exception of AxisOut, which is a single-ended output.
There are no associated connections required for these signals to function properly, however, one or more of the
digital grounds must be connected. The input signals are pulled up through 4.7 kOhm resistors to 5V. The default
power-up value for all
AxisOut
signals is high.
See Chapter 4, Electrical Reference , on page 69 for a complete description of the pinout connections to and from the
card.
2.7.2 QuadA, QuadB, Index
These signals provide position feedback to the motion controller which is used to track motor position. For DC brush
and brushless DC motors, they are required for proper operation. For microstepping or step (pulse & direction)
motors, they are optional.
The typical write time to the non-volatile RAM is 30

Sec, however it may take as long as several 100 mSec. If
other portions of the user application code, or any other PRP-connected device, depends on these values having
been written, it is recommended that you ensure that the write operation has completed by adding code that
explicitly checks the value, or by waiting a fixed period of time after the NVRAM write operation