Tektronix FCA3000 Series, Programmer'S Manual

Page: 85 / 191

Command Descriptions
INPut{[1]|2}:LEVel:AUTO
If set to AUTO, the instrument automatically controls the trigger level.
The autotrigger function normally sets the trigger levels to 50 % of the signal
amplitude, except for the following measurements or modes:
Rise/Fall time measurements: Here the Input 1 (A) trigger level is set to 10%
resp. 90% and the Input 2 (B) trigger level is set to 90% respectively. 10%
of the amplitude.
Frequency and Period Average mode: The input trigger levels are set to 70%
and 30% of the signal amplitude.
Functions for which AUTO does not work are Frequency or Period
Back-to-Back, Time Interval Error (TIE) and Totalize. If one of these is
selected, an AUTO ONCE is performed instead.
Group Input
Syntax
INPut{[1]|2}:LEVel:AUTO {<Boolean> | ONCE}
INPut{[1]|2}:LEVel:AUTO?
Arguments
INPut{[1]|2}
speci fi es the input channel to set (1 = A, 2 = B). If no value is
entered for this argument, the command sets the attenuation for Input A.
<BOOLEAN>
= {1 | ON} | {0 | OFF}.
ONCE
sets the instrument to make one automatic calculation of the trigger level at
the beginning of a measurement. This value is then used until another level-setting
command is sent to the instrument, or until a new measurement is initiated.
INPut{[1]|2}:LEVel:RELative
When autotrigger is active, the relative trigger levels are normally fi xed at
values that depend on the selected function, for instance 10% (Input A) and
90% (Input B) for Rise Time, 50% (Input A & Input B) for Time Interval, 70%
(Input A) and 30% (Input B) for Frequency. At times you may want to change
these values. Since the default values are restored automatically after changing
function, this command may have to be sent repeatedly. The two input channels
are programmed separately and are not interdependent.
The command itself does not switch on autotrigger, so if you want to set relative
levels after having used absolute levels, you must also send the command
INPut{[1]|2}:LEVel:AUTO , unless you have changed measurement function.
Group Input
FCA3000, FCA3100, MCA3000 Series Programmer Manual 2-69