IviScope Read Waveform Measurement
IviScopeWaveformMeas Capability Group [WM]
This VI initiates an acquisition on all channels that you enable with the IviScope Configure Channel VI. If the channel you specify in the Channel Name parameter is not enabled for the acquisition, this VI returns the IVISCOPE_ERROR_CHANNEL_NOT_ENABLED error. It then waits for the acquisition to complete and returns the waveform measurement for the channel you specify. If the oscilloscope did not complete the acquisition within the time period you specify with the Maximum Time parameter, the VI returns the IVISCOPE_ERROR_MAX_TIME_EXCEEDED error.
You call the IviScope Fetch Waveform Measurement [WM] VI to obtain any other waveform measurement on a specific channel without initiating another acquisition.
Notes
|
instrument handle The instrument handle that you obtain from the IviScope Initialize or the IviScope Initialize With Options VI. | |
channel name Pass the virtual channel name that you assign to the instrument in MAX from which you want to read a waveform measurement.
Virtual channel names are aliases for instrument specific channel strings. The instrument specific channel strings can differ from one instrument to another. Virtual channel names allow you to use and swap instruments without having to change the channel names in your source code. You assign a virtual channel name to an instrument specific channel in MAX. This control accepts virtual channel names you have assigned to the specific instrument you are using. It also accepts the instrument specific channel names. Default Value: "" |
|
measurement function Pass the waveform measurement you want the oscilloscope to perform.
Defined values: IVISCOPE_VAL_RISE_TIME—Rise Time IVISCOPE_VAL_FALL_TIME—Fall Time IVISCOPE_VAL_FREQUENCY—Frequency IVISCOPE_VAL_PERIOD—Period IVISCOPE_VAL_VOLTAGE_RMS—Voltage RMS IVISCOPE_VAL_VOLTAGE_CYCLE_RMS—Voltage RMS (Cycle) IVISCOPE_VAL_VOLTAGE_MAX—Voltage Max IVISCOPE_VAL_VOLTAGE_MIN—Voltage Min IVISCOPE_VAL_VOLTAGE_PEAK_TO_PEAK—Voltage Vpp IVISCOPE_VAL_VOLTAGE_HIGH—Voltage High IVISCOPE_VAL_VOLTAGE_LOW—Voltage Low IVISCOPE_VAL_VOLTAGE_AVERAGE—Voltage Avg. IVISCOPE_VAL_VOLTAGE_CYCLE_AVERAGE—Voltage Avg. (Cycle) IVISCOPE_VAL_WIDTH_NEG—Width Negative IVISCOPE_VAL_WIDTH_POS—Width Positive IVISCOPE_VAL_DUTY_CYCLE_NEG—Duty Cycle Negative Duty Cycle Negative = 100.0 x (Width Negative)/Period IVISCOPE_VAL_DUTY_CYCLE_POS—Duty Cycle Positive Duty Cycle Positive = 100.0 X (Width Positive)/Period IVISCOPE_VAL_AMPLITUDE—Amplitude IVISCOPE_VAL_OVERSHOOT—Overshoot For the rising edge: For the falling edge: IVISCOPE_VAL_PRESHOOT—Preshoot For the rising edge: PRESHOOT = ((Voltage Low - local minimum)/Amplitude)*100%where the local minimum is the minimum value of the signal measured in the second half of the time period that commences when the preceding falling edge crosses the low reference level and concludes when the rising edge crosses the low reference level. For the falling edge: Default Value: IVISCOPE_VAL_RISE_TIME |
|
Note You must configure the appropriate reference levels before you call this VI. You configure the low, mid, and high references either by calling the IviScope Configure Reference Levels [WM] VI or by setting the following properties: IviScope Measurement High Reference [WM] IviScope Measurement Low Reference [WM] IviScope Measurement Mid Reference [WM] |
|
maximum time (ms) Pass the maximum length of time in which to allow the read waveform measurement operation to complete.
If the operation does not complete within this time interval, the VI returns the IVISCOPE_ERROR_MAX_TIME_EXCEEDED error code. When this occurs, you can call IviScope Abort to cancel the read waveform operation and return the oscilloscope to the Idle state. Units: milliseconds. Defined Values: IVISCOPE_VAL_MAX_TIME_INFINITE IVISCOPE_VAL_MAX_TIME_IMMEDIATE Default Value: 5000 (ms) |
Note The Maximum Time parameter applies only to this VI. It has no effect on other timeout parameters or properties. |
error in (no error) The error in cluster can accept error information wired from VIs previously called. Use this information to decide if any functionality should be bypassed in the event of errors from other VIs.
The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed. |
|
instrument handle out The instrument handle that you obtain from the IviScope Initialize or the IviScope Initialize With Options VI. | |
measurement Returns the measured value.
Units The units depend on the Measurement Function you select, as shown below: Rise Time—seconds Fall Time—seconds Frequency—hertz Period—seconds Voltage RMS—volts Voltage RMS (Cycle)—volts Voltage Max—volts Voltage Min—volts Voltage Vpp—volts Voltage High—volts Voltage Low—volts Voltage Avg.—volts Voltage Avg. (Cycle)—volts Width Negative—seconds Width Positive—seconds Duty Cycle Negative—percentage Duty Cycle Positive—percentage Amplitude—volts Overshoot—percentage Preshoot—percentage |
|
error out The error out cluster passes error or warning information out of a VI to be used by other VIs.
The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed. |