Trigger Mode and Conditioning 11
Keysight InfiniiVision HD3-Series Oscilloscopes User's Guide 155
In either Auto or Trig'd trigger mode, a trigger may be missed if the event occurs
while the pre-trigger buffer is being filled. This may be more likely, for example,
when the horizontal scale knob is set to a slow time/div setting, such as
500 ms/div.
Trigger Indicator The trigger indicator in the trigger badge shows whether triggers are occurring.
In the Auto trigger mode, the trigger indicator can show:
• Auto? — the trigger condition is not found (after the pre-trigger buffer has
filled), and forced triggers and acquisitions are occurring.
• Auto — the trigger condition is found (or the pre-trigger buffer is being filled).
In the Trig'd trigger mode, the trigger indicator can show:
• Trig'd? — the trigger condition is not found (after the pre-trigger buffer has
filled), and no acquisitions are occurring.
• Trig'd — trigger condition is found (or pre-trigger buffer is being filled).
When the oscilloscope is not running, the trigger indicator area shows Stop.
When to Use Auto
Trigger Mode
The Auto trigger mode is appropriate when:
• Checking DC signals or signals with unknown levels or activity.
• When trigger conditions occur often enough that forced triggers are
unnecessary.
When to Use Trig'd
Trigger Mode
The Trig'd trigger mode is appropriate when:
• You only want to acquire specific events specified by the trigger settings.
• Triggering on an infrequent signal from a serial bus (for example, I2C, SPI, CAN,
LIN, etc.) or another signal that arrives in bursts. The Trig'd trigger mode lets
you stabilize the display by preventing the oscilloscope from auto-triggering.
• Making single-shot acquisitions with the [Single] key.
Often with single-shot acquisitions, you must initiate some action in the device
under test, and you don't want the oscilloscope to auto-trigger before that
happens. Before initiating the action in the circuit, wait for the trigger condition
indicator Trig'd? to display (this tells you the pre-trigger buffer is filled).
See Also •
"Forcing a Trigger" on page 137
• "To set the trigger holdoff" on page 158
• "To position the time reference (left, center, right, custom)" on page 50
To select the trigger coupling
1 Open the Conditioning dialog box by selecting Conditioning... in the Trigger
dialog box or by choosing choose Trigger > Conditioning... from the main menu.
2 In the Conditioning dialog box, select the Coupling tab.
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