Tektronix TDS 500C User Manual

Triggering on Waveforms

TDS 500C, TDS 600B, & TDS 700C User Manual

 The Trigger When side menu indicates the oscilloscope will trigger on pulses

with slew rates slower than the slew rate setting. Since the pulse edge slews
at 20 mV/ns, which is faster than the slew rate setting of 16 mV/ns, the
oscilloscope triggers.

 The trigger point indicator shows where the oscilloscope triggers. For a slew

rate triggered waveform, the trigger point is always at the threshold crossed last
(the upper threshold for positive polarity settings; the lower for negative
settings).

Set the Mode and Holdoff. Mode and holdoff can be set for all standard trigger
types and classes. To set mode and holdoff, refer to Set Mode & Holdoff on
page 3–75. To learn more about trigger mode and holdoff, see Trigger Modes
and Trigger Holdoff on page 3–65.

When you select the pulse class Timeout, the TDS oscilloscope will trigger on a
pulse change that does NOT occur within the specified limits. That is, the trigger
will occur when, depending on the polarity you select, the signal stays higher or
stays lower than the trigger level for the timeout value. To set up for timeout
triggering, do the following procedures.

Select Timeout Triggering. Press TRIGGER MENU ➞ Type (main) ➞ Pulse
(pop-up) ➞ Class (main) ➞ Timeout (pop-up).

Select the Source. Press TRIGGER MENU ➞ Type (main) ➞ Pulse
(pop-up) ➞ Source (main) ➞ Ch1, Ch2, Ch3, or Ch4 (side). The source
selected becomes the trigger source for all four trigger classes.

Select the Polarity. Press TRIGGER MENU ➞ Type (main) ➞ Pulse
(pop-up) ➞ Class (main) ➞ Timeout (pop-up) ➞ Polarity (main) ➞ Stays
High, Stays Low, or Either (side).

Stays High causes a trigger to occur if the signal stays higher than the
trigger level for longer than the timeout value.

Stays Low causes a trigger to occur if the signal stays lower than the trigger
level for longer than the timeout value.