HP E1433A User Manual page 74

HP E1433A User's Guide
Using the HP E1433A
After firmware is installed, and after a call to hpe1432_preset, all of the
parameters (both channel-specific and global) in an HP E1433A module are
set to their default values. For channel-specific parameters, the default
value may depend on the type of channel. Some channel-specific
parameters apply only to a specific type of channel. For example, tach
holdoff applies only to tach channels. Setting such a parameter for a
channel that doesn't make sense will result in an error.
At the start of a measurement, the HP E1433A firmware sets up all
hardware parameters, and ensures that the input hardware is settled before
starting to take data. The firmware also ensures that any digital filters have
time to settle. This ensures that all data read from the module will be valid.
However, after a measurement starts, HP E1433A parameters can still be
changed. The effect of this change varies, depending on the parameter.
For some parameters, changing the value aborts the measurement
immediately. For other parameters, the measurement is not aborted, but
the changed parameter value is saved and not used until a new
measurement is started. For still other parameters, the parameter change
takes place immediately, and the data coming from the module may contain
glitches or other effects from changing the parameter. See the chapter
titled "The C-Language Host Interface Library" for Parameter Lists showing
the effects for each parameter. Parameter names for the VXIplug&play
library are similar to those for the C-Language Host Interface Library.
You cannot tell the module to wait for settling when changing a parameter
in the middle of a measurement. The only way to wait for settling is to
stop and re-start the measurement. Also, you cannot disable the settling
that takes place at the start of a measurement.
Refer to the (on-line) HP E1433A Function Reference for the parameters
needed for each function. (See "Where to get more information" in this
chapter.)
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