NI ELVISmx Oscilloscope

NI ELVISmx Help

Edition Date: June 2015

Part Number: 372500F-01

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Acquires and displays data for one or two channels. The NI ELVISmx Oscilloscope supports analog and digital triggering. For digital triggering, you must connect a TTL-level signal to the TRIG line on the NI ELVIS II Series Workstation. For analog triggering, you can set the trigger level and slope.

Dialog Box Options
Block Diagram Inputs
Block Diagram Outputs
How to Measure Signals Using the NI ELVISmx Oscilloscope

Dialog Box Options

ParameterDescription
Autoscale graph Specifies whether to autoscale the X-Y scale of the graph. If autoscaling is enabled, the X-Y scale of the graph is autoscaled each time the graph is updated. If autoscaling is disabled, the X-Y scale of the graph maintains its settings.

Configuration Tab

Parameter Description
Instrument Control Contains the following options:
  • Device—Specifies the device to use.
  • Channel 0 Enable—Specifies whether to enable data acquisition on Channel 0. If checked, data acquisition is enabled. If unchecked, data acquisition is disabled.
  • Channel 1 Enable—Specifies whether to enable data acquisition on Channel 1. If checked, data acquisition is enabled. If unchecked, data acquisition is disabled.
  • Auto Setup—Automatically sets the oscilloscope parameters to acquire a signal. If you use Auto Setup, the Sample Rate, Record length, and Range are set for you.
Vertical (Channel 0 tab) Channel 0 appears only if the Channel 0 checkbox is enabled.
  • Source—Selects the signal source for the measurement on CH 0. You can select:
    • Scope CH 0—Channel 0 is one of the SCOPE BNC connectors on the control panel.
    • AI <0..7>—These channels are available on the NI ELVIS Prototyping Board.
Note Note  (NI ELVIS II+ only) SCOPE channels cannot be used with AI channels.
  • Range (V)—Specifies the value of the input range the oscilloscope uses for the channel. For example, to acquire a sine wave that spans from –5.0 volts to 5.0 volts, set the Range to 5.0.
  • Coupling—Specifies the coupling for the channel. This operation is done in the software. You can select:
    • DC (default)—Measures the entire signal. DC is the only supported coupling mode when the device is configured for MIO. DC is always the value for AI channels.
    • AC—Removes the DC offset from the signal. AC is only available on ELVIS II and ELVIS II+ Scope channels.
    • GND(NI ELVIS II+ SCOPE channels only) Disconnects from the input signal and connects to ground. GND is useful for determining zero references.
  • Probe—Selects the probe value. The possible values are 1x or 10x. The default is 1x.
Vertical (Channel 1 tab) Channel 1 appears only if the Channel 1 checkbox is enabled.
  • Source—Selects the signal source for the measurement on CH 1. You can select:
    • Scope CH 1—Channel 1 is one of the SCOPE BNC connectors on the control panel.
    • AI <0..7>—These channels are available on the NI ELVIS Prototyping Board.
Note Note  (NI ELVIS II+ only) SCOPE channels cannot be used with AI channels.
  • Range (V)—Specifies the value of the input range the oscilloscope uses for the channel. For example, to acquire a sine wave that spans from –5.0 volts to 5.0 volts, set the Range to 5.0.
  • Coupling—Specifies the coupling for the channel. This operation is done in the software. You can select:
    • DC (default)—Measures the entire signal. DC is the only supported coupling mode when the device is configured for MIO. DC is always the value for AI channels.
    • AC—Removes the DC offset from the signal. AC is only available on ELVIS II and ELVIS II+ Scope channels.
    • GND(NI ELVIS II+ SCOPE channels only) Disconnects from the input signal and connects to ground. GND is useful for determining zero references.
  • Probe—Selects the probe value. The possible values are 1x or 10x. The default is 1x. Probe is available only for ELVIS II and ELVIS II+ Scope channels and is not available for MIO channels.
Horizontal Contains the following options:
  • Sample rate (S/s)—Specifies the sampling rate for the acquisition.
  • Record length—Specifies the number of points acquired at each run.
    Note Note  System memory considerations may limit the maximum number of points to approximately 10 million for NI ELVIS II channels and NI ELVIS II+ MIO channels, and 16k for NI ELVIS II+ SCOPE channels.
  • Acquire—Specifies the acquisition mode of the Express VI. The following modes are available:
    • N Samples—Each time the VI is called, it returns a finite number of samples. This set of samples is not phase continuous with the previous acquisition.
    • Continuously—The first time the VI is called, it initiates a continuous acquisition on the oscilloscope. Subsequent calls retrieve the next set of data, phase continuous with the previous set, from the oscilloscope. The maximum acquisition rate that can be sustained without error depends on the hardware/software configuration.

Trigger Settings Tab

ParameterDescription
Trigger Contains the following options:
  • Type—Specifies the type of trigger to start the acquisition. The default is Immediate. Select from the following options:
    • Immediate—There is no external signal that triggers the acquisition—the acquisition begins immediately.
    • Digital—A digital trigger occurs on either a rising edge or falling edge of a digital signal. You can specify the Slope as either positive (on the rising edge) or negative (on the falling edge) to the trigger. When Digital triggering is chosen, the Trigger Source control is set to TRIG.
    • Edge—An edge trigger occurs when a signal crosses a trigger threshold that you specify in the Level (V) control. You can specify the Slope as either positive (on the rising edge) or negative (on the falling edge) to the trigger. When Edge triggering is chosen, the Trigger Source control can be set to Chan 0 Source or Chan 1 Source.
  • Source—Specifies the source for the external start trigger for the Oscilloscope data acquisition. Select the following options.
    • TRIG—The trigger source is the TRIG input on the NI ELVIS II Series Workstation.
    • SYNC—The trigger source is the SYNC output on the NI ELVIS II Series device or workstation. SYNC is only allowed when the trigger type is Digital.
    • Chan 0 Source—The trigger source is the channel specified by the Channel 0 Source control on the Configuration tab.
    • Chan 1 Source—The trigger source is the channel specified by the Channel 1 Source control on the Configuration tab.
  • Slope—Determines whether to trigger off of a leading edge (Positive) or a trailing edge (Negative) for digital triggers, or a rising slope (Positive) or a falling slope (Negative) for analog triggers. The default is Positive.
  • Level (V)—Specifies the voltage at which a trigger occurs. This parameter is only valid when Type is set to Edge. The default is 0.
  • Horizontal Position (%)—Specifies the trigger position as a percentage of total time acquired. The default is 50%. When the Horizontal Position control is disabled, the trigger will occur at the start measurement. This control is disabled if:
    • ELVIS II+—The trigger Type control is set to Edge, both channels are enabled, and both channels are set to AI.
    • ELVIS II—The trigger Type control is set to Edge and both channels are enabled.

Advanced Configuration Tab (NI ELVIS II+ SCOPE channels only)

Parameter Description
Channel 0 Contains the following options:
  • Vertical Offset (V)—Specifies the voltage the vertical range is centered on. The value is with respect to ground and is in volts.
  • 20 Mhz Filter—Enables/Disables a 20 MHz low-pass noise filter.
    Note Note  Vertical Offset and 20 MHz Filter can only be set when using NI ELVIS II+ SCOPE channels. Using these settings with the NI ELVIS II or NI ELVIS II+ MIO channels may cause errors.
Channel 1 Contains the following options:
  • Vertical Offset (V)—Specifies the voltage the vertical range is centered on. The value is with respect to ground and is in volts.
  • 20 Mhz Filter—Enables/Disables a 20 MHz low-pass noise filter.
    Note Note  Vertical Offset and 20 MHz Filter can only be set when using NI ELVIS II+ SCOPE channels. Using these settings with the NI ELVIS II or NI ELVIS II+ MIO channels may cause errors.

Block Diagram Inputs

ParameterDescription
Device Name Specifies the name of the I/O device in use.
Stop Specifies to stop the task and release device resources when this Express VI completes execution. This input is TRUE by default, meaning the task stops after all samples are acquired or generated. For continuous operations, put the Express VI in a While Loop and wire the stop input to the same stop control you wire to the conditional terminal on the While Loop. This will prevent the task from being reconfigured with each iteration of the loop, as well as stop the task and release the resources when the While Loop is stopped.
Channel 0
  • For ELVIS II, specifies the Source, Range (V), Coupling, and Probe for Channel 0.
  • For ELVIS II+, specifies the Source, Range (V), Coupling, Probe, Offset, and Filter for Channel 0.
    Note Note  Offset and Filter can only be set when using NI ELVIS II+ SCOPE channels. Using these settings with the NI ELVIS II or NI ELVIS II+ MIO channels may cause errors.
CH0 Enable Specifies whether to enable data acquisition on Channel 0.
Channel 1
  • For ELVIS II, specifies the Source, Range (V), Coupling, and Probe for Channel 1.
  • For ELVIS II+, specifies the Source, Range (V), Coupling, Probe, Offset, and Filter for Channel 1.
    Note Note  Offset and Filter can only be set when using NI ELVIS II+ SCOPE channels. Using these settings with the NI ELVIS II or NI ELVIS II+ MIO channels may cause errors.
CH1 Enable Specifies whether to enable data acquisition on Channel 1.
Horizontal Specifies the Sample Rate, Record length, and Acquire method.
Trigger Specifies the Source, Slope, Type, Level (V), and Horizontal Position (%).
error in Describes error conditions that occur before the VI runs.

Block Diagram Outputs

ParameterDescription
ELVIS/Channel0 Contains the samples read from Channel 0. Channel 0 must be enabled for data to be returned.
ELVIS/Channel1 Contains the samples read from Channel 1. Channel 1 must be enabled for data to be returned.
error outContains error information. If error in indicates that an error occurred before this VI ran, error out contains the same error information. Otherwise, it describes the error status that this VI produces.

How to Measure Signals Using the NI ELVISmx Oscilloscope

Complete the following steps to use the NI ELVISmx Oscilloscope to measure a signal.

  1. Connect the signal(s) you want to measure and the trigger signal, if desired, to the BNC connector(s) on the side of the NI ELVIS II Series Workstation.
    Note Note  For more information on grounding the signals, refer to the NI ELVIS II Series User Manual.
  2. Add the NI ELVISmx Oscilloscope to your application.
  3. Select to measure Channel 0, Channel 1, or both. Select the Channel 0 checkbox to measure Channel 0. Select the Channel 1 checkbox to measure Channel 1. Select the Channel 0 and Channel 1 checkboxes to measure both channels.
  4. Set up the horizontal and vertical properties of the channel(s).
  5. Click the Run button to acquiring the measurement. You should see the signal in the display window.
  6. If necessary, click the Auto Setup button to automatically configure the oscilloscope parameters to acquire the signal, or explicitly set the Sample Rate and Record Length. You can also configure the measurement to acquire N samples or acquire Continuously.
  7. If necessary, switch to the Trigger tab and adjust the controls to stabilize the signal in the graph. If you have an external signal connected as the trigger signal, select Digital as the trigger Type. If you want to use one of the input channels as the trigger, select Edge as the trigger Type and choose Chan 0 Source or Chan 1 Source from the trigger Source control. To change the position of the trigger in the graph, adjust the Horizontal Position (%) control.

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