User`s guide

12 Troubleshooting
12-22
Round this number to the nearest whole number of 117 ticks. The resulting
frequency is then
(116.96 ticks/117)(50) = 49.983 Hz
The difference between the expected and measured signal is .019, which
deviates from the expected signal value by .038% (.019/50.002). The deviation
when the sample time is 1/10000 is .04%.
Some amount of error is common for most PCs, and the margin of error varies
from machine to machine.
Note Most high-level operating systems, like Windows or Linux, occasionally
insert extra long intervals to compensate for errors in the timer. Be aware
that xPC Target does not attempt to compensate for timer errors. This is
because for xPC Target, close repeatability is more important for most models
than exact timing. However, some chips might have inherent designs that
produce residual jitters that could affect your system. For example, some
Pentium chips might produce residual jitters on the order of .5 microsecond
from interrupt to interrupt.
Why Did I Get Error -10: Invalid File ID on the Target PC?
You might get this error if you are acquiring signal data with a scope of type
file. This error occurs because the size of the signal data file exceeds the
available space on the disk. The signal data will most likely be corrupted and
irretrievable. You should delete the signal data file and reboot the xPC Target
system. To prevent this occurrence, monitor the size of the signal data file as
the scope acquires data.
Refer to The MathWorks Support xPC Target Web site
(
http://www.mathworks.com/support/product/XP) for additional
information.
Can I Write Custom xPC Target Device Drivers?
You might want to write your own driver if you want to include an unsupported
device driver in your xPC Target system. The xPC Target documentation does
not currently describe how to write your own xPC Target device drivers. Refer
to the following for further information: