HP 8-Channel 196 kSa/sec Digitizer plus DSP E1433A HP E1433A Parameters, For More Information

HP E1433A User's Guide

The C-Language Host Interface Library

HP E1433A Parameters

Some parameters, such as range or coupling, apply to specific channels. When a channel ID is given to a function that sets a channel-specific parameter, only that channel is set to the new value.

Some parameters, such as clock frequency or data transfer mode, apply globally to a module. When a channel ID is used to change a parameter that applies to a whole module, the channel ID is used to determine which module. The parameter is then changed for that module.

Starting and stopping a measurement is somewhat like setting a global parameter. Starting a measurement starts each active channel in each module that has a channel in the group.

After firmware is installed, and after a call to e1432_preset, all of the parameters (both channel-specific and global) in an HP E1432A 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.

There is no way to 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, there is no way to disable the settling that takes place at the start of a measurement.

For More Information

Refer to the (on-line) HP E1432A Function Reference for a list of all functions and the parameters needed for each function. (See “Where to get more information” in the chapter titled “Using the HP E1433A).”

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