NI-TClk Synchronization Help

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NI-TClk Homogeneous and Heterogeneous Triggers

NI-TClk Homogeneous and Heterogeneous Triggers

NI-TClk provides a simplified interface for synchronizing systems with homogeneous triggers in a single PXI chassis or PC. NI-TClk also provides a flexible interface for other supported systems.

Triggers Supported by NI-TClk

The following table summarizes the triggers supported by NI-TClk.

Trigger Acquisition Generation
Start Trigger
Yes
Yes
Reference Trigger
Yes
N/A
Script Trigger
0 – 3
N/A
Yes
Pause Trigger
No
Yes

Individual instruments may support some or all of the triggers listed in the previous table. Instruments may also support triggers other than those listed in the previous table. These other triggers, as well as Pause Triggers for acquisition sessions, are not supported by NI-TClk and are not relevant to the definition of homogeneous triggers. For information about which triggers your device supports, refer to the device documentation.

Homogeneous Triggers

If the triggers in synchronized sessions are synchronized, these triggers are considered homogeneous triggers.

Note  When you do not configure a supported trigger, the trigger is referred to as None. Refer to Comparison of Terminology between NI-TClk, NI-HSDIO, NI-SCOPE, and NI-FGEN for more information about trigger terminology.

For each of the other triggers supported by NI-TClk, one of the following conditions must be true:

  • The trigger is not supported by any of the sessions.
  • The trigger is configured to None by all sessions that support it.
  • One of the sessions, called the trigger master session, is configured to receive the trigger from the external world (in case of external triggers) or to generate that trigger (in case of None or software triggers), and the corresponding trigger on all other sessions is configured so that it comes from the trigger on the trigger master session.

If there is a trigger master session, non-master sessions must use the triggers that they receive from the trigger master session for the same purpose as the trigger master session. For example, the Reference Trigger from the reference trigger master session must be used as the Reference Trigger for the non-master sessions.

The type of trigger for the trigger master session is not relevant for this definition. The type of trigger for non-master sessions must be digital edge or digital level because the trigger generated by the trigger master is a digital signal.

With TClk synchronization, all sessions react to a synchronized trigger at the same time.

Heterogeneous Triggers

Sessions that do not have homogenous triggers, have heterogeneous triggers. If the session does not fulfill any of the conditions that are specified in the homogeneous triggers section, these sessions have heterogeneous triggers.

Examples

Example 1: Homogeneous Triggers

Sessions A and B have triggers as indicated in the following table. Sessions A and B have homogeneous triggers.

Trigger Session A
(Generation)
Session B
(Generation)
Start Trigger Software Trigger Start Trigger from session A
Reference Trigger Not supported Not supported
Script Trigger
0 – 3
Not supported Not supported
Pause Trigger Not supported Not supported


Example 2: Homogeneous Triggers

Sessions A, B, C, and D have triggers as indicated in the following table. Sessions A, B, C, and D have homogeneous triggers. Notice that session A is the master session for the Start Trigger, and session B is the master session for the Reference Trigger.

Trigger Session A
(Acquisition)
Session B
(Acquisition)
Session C
(Generation)
Session D
(Generation)
Start Trigger None Start trigger from session A Start trigger from session A Start trigger from session A
Reference Trigger Reference Trigger from session B Analog edge Trigger Not supported Not supported
Script Trigger
0 – 3
Not supported Not supported None None
Pause Trigger Not supported Not supported None None


Example 3: Heterogeneous Triggers

Sessions A, B, and C have triggers as indicated in the following table. Sessions A, B, and C have heterogeneous triggers because neither the Script Trigger nor the Pause Trigger comply with any of the three required conditions to be a homogeneous trigger.

Trigger Session A
(Generation)
Session B
(Generation)
Session C
(Generation)
Start Trigger Software Trigger Start Trigger from session A Start Trigger from session A
Reference Trigger Not supported Not supported Not supported
Script Trigger 0 Digital edge None None
Script Trigger
1 – 3
None None None
Pause Trigger None Digital level Pause Trigger from session B


Related Topics

niTClk Configure For Homogeneous Triggers VI

niTClk_ConfigureForHomogeneousTriggers function

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