The following diagram depicts the state model for the DST instrument when programmed with DSTA software to acquire data in the I/Q mode.

—State transitions caused by software

—Output signals

—User-configurable state transitions caused by software or hardware

—State transitions caused by the internal state machine of the instrument

The states are as follows:

Configuration—(Idle) The instrument is not sampling a waveform. All session properties are programmable in this state. Properties may not have been applied to hardware yet, so the hardware configuration of the module may not match the values of the properties in the session. In addition, the instrument remains configured as it was the last time a session was committed. If you recently reset the computer, the instrument is in the Idle state. Call Initiate to program all of the properties to the hardware and move to the Committed state.

Committed—All of the properties are programmed to the instrument. Initiate an acquisition to move to the Wait for Start Trigger state.

Note You can change the I Gain, Q Gain, I Offset, Q Offset, Frequency Offset, and Phase attributes without aborting the acquisition.

Wait for Start Trigger—The instrument transitions to this state when you initiate an acquisition. When the instrument recognizes a trigger condition, it transitions from this state on the next clock cycle and generates a Start Trigger.

• If you configure the Start Trigger source as None (default), the instrument immediately transitions from this state and generates a Start Trigger.
• If you configure the Start Trigger source as a software or hardware trigger from one of the available sources, the instrument remains in this state until the configured trigger occurs.

The default Start Trigger source is None.

Minimum Pre-Reference Trigger Sampling—The instrument transitions into this state in the following ways:

• Receiving the Start Trigger from the Start Trigger source.
• Receiving the Advance Trigger from the Advance Trigger source.

The transition into this state depends on the previous state of the instrument. While in this state, the instrument samples according to the session attributes configured. The module remains in this state until three conditions are satisfied:

• The minimum Pre-Reference Trigger sampling completes
• The trigger-to-trigger delay has expired

The first time through this state, the trigger-to-trigger delay does not have an effect. When the three conditions are satisfied, the instrument transitions from this state on the next clock cycle. Use the Pretrigger Samples property to specify the number of samples to acquire before the Reference Trigger is received.

Wait for Reference Trigger while Sampling—The instrument transitions into this state after the instrument finishes the Minimum Pre-Reference Trigger Sampling state. When the instrument recognizes a trigger condition, the instrument transitions from this state.

• If you configure the Reference Trigger source as None (default), the instrument immediately transitions from this state and generates a Reference Trigger.
• If you configure the Reference Trigger source as a software or hardware trigger from one of the available sources, the instrument remains in this state until the configured trigger occurs.

The default Reference Trigger source is None.

Post-Reference Trigger Sampling—After the instrument receives the Reference Trigger, the instrument transitions into this state. The instrument begins sampling Post-Reference Trigger samples according to the properties configured for the session. When the Post-Reference Trigger sampling completes, the instrument transitions from this state.

Record Completed—After the instrument completes Post-Reference Trigger Sampling state, the instrument transitions into this state. The instrument leaves this state after the current record has been stored in the onboard memory. Upon leaving this state, the instrument generates an End of Record Event.

Wait for Advance Trigger—After the instrument has completed a record and determines that there are additional records to complete, the instrument transitions into this state. When the instrument recognizes a trigger condition, the instrument transitions from this state.

• If you configure the Advance Trigger source as None (default), the instrument transitions from this state on the next clock edge.
• If you configure the Advance Trigger source as a software or hardware trigger from one of the available sources, the instrument remains in this state until the configured trigger occurs.

The default Advance Trigger source is None.

Acquisition Completed—(Done) After the instrument completes a record and determines that all the records are done, it transitions into this temporary state and generates the End of Acquisition Event. The software transitions the instrument from this state and back to the Idle state when you call a Fetch function or DSTA Check Acquisition Status.