A sequence contains steps that specify a series of outputs for an NI-DCPower channel. In a simple sequence, you can specify a series of voltage outputs or a series of current outputs. Advanced sequencing allows you to configure multiple properties per sequence step.

For more information on using and customizing advanced sequences, refer to Advanced Sequencing.

During a sequence, the channel steps through a predetermined set of NI-DCPower configurations without any interaction with the host system and NI-DCPower. Because the host system does not execute the NI-DCPower sequence changes, the changes from one step in the sequence to the next are deterministic.

Support For Sequence Mode

  • The PXI-4110 and PXI-4130 devices do not support this feature.
  • The system does not support using the NI-DCPower Set Sequence and Advanced Sequence functions for the same channel in the same session.

Typical Sequence Operation

The following steps illustrate the typical operation of the source unit when you initiate in Sequence source mode.

  1. (Optional, only for Advanced sequencing) The driver applies the Commit step to the channel if the system meets the following conditions:
    • The channel was previously in the Uncommitted state.
    • You created a Commit step.
    As a result, the source unit does the following:
    1. The source unit applies the voltage or current specified by the Commit step.
    2. The source unit waits for the source delay specified by the Commit step.
    Note The Commit step in an advanced sequence does not generate a Source Complete event.
  2. (Optional) The source unit waits for a Start Trigger.
  3. The channel steps through the sequence.
    1. (Optional) If this step is not the first step in the sequence, the source unit waits for a Source trigger.
    2. The source unit applies the voltage or current in the next sequence step.
    3. The source unit waits the time that the next source delay in the sequence specifies. After, the source unit generates a Source Complete event.
    4. (Optional) The measure unit takes a measurement and stores it in a buffer on the instrument.
      Note The presence of this step is dependent on the settings of NI-DCPower Measure When. If you set the Measure When property to Automatically After Source Complete, the measure unit takes a measurement after each source step. Otherwise, the measure unit operates independently of the source unit.
    5. The source unit repeats 3a through 3d for every step in the sequence.
  4. The sequence iteration is complete. The source unit generates the Sequence Iteration Complete event.
  5. (Optional) The source unit loops back and repeats the same sequence. When it loops back, the source unit waits for a Sequence Advance trigger (if it is not disabled). Then, the source unit runs through the sequence again without waiting for the Start trigger.
  6. The seeuqence operation completes in the following cases:
    • If you set the NI-DCPower Sequence Loop Count Is Finite to True, the sequence runs the number of times that is specified by the NI-DCPower Sequence Loop Count property. Once the sequence reaches the number, the operation is complete. NI-DCPower generates the Sequence Engine Done event, as illustrated in the following figures.
    • If you set the NI-DCPower Sequence Loop Count Is Finite to False, the sequence ignores the NI-DCPower Sequence Loop Count property. The sequence returns to step 3a until you abort it. You can abort the sequenc by calling the NI-DCPower Abort With Channels or by closing the session.

The following figure illustrates a sequence under the following conditions:

  • NI-DCPower Measure When is set to Automatically After Source Complete.
  • The source unit is not pulsing.

A flowchart of a sequence when the NI-DCPower Measure When is set to Automatically After Source Complete and the source unit is not pulsing.

The following figure illustrates a sequence under the following conditions:

  • NI-DCPower Measure When is not set to Automatically After Source Complete.
  • The source unit is not pulsing.

A flowchart of a sequence when the NI-DCPower Measure When is not set to Automatically After Source Complete and the source unit is not pulsing.