User manual

22
Trigger System
MENU section. Selecting the corresponding soft menu
item allows you to set any of these settings for positively
(POS.) or negatively polarized pulses (NEG.). For the asso-
ciatedpositivepulse,youdenethewidthfromrisingto
falling slopes, and accordingly for the associated negative
pulse from falling to rising slopes. As is consistent with the
principle, triggering always occurs on the second slope of
the pulse.
6.3.3 Logic Trigger
Selecting the LOGIC trigger in the soft menu after pressing
the TYPE key
31
will switch the trigger source to the digital
inputs. Pressing the SOURCE key
32
after selecting this
trigger type displays a soft menu for additional settings
and a window to list these settings.
The soft menu key LOGIC CHANNEL enables you to select
a logic channel for which you wish to determine the trigger
condition. Use the universal knob in the CURSOR/MENU
section for this purpose. In the general menu, the selected
digitalinputismarkedwithabluebackground.Intheeld,
the trigger level is marked as High (H), Low (L) or (X). Use
the corresponding soft menu key to select the trigger level.
The soft menu item COMBINATION allows the logic com-
bination of the digital channels. They can be combined by
logic AND or OR. If AND is selected, the set conditions
of all channels must be met simultaneously for the input
signal so that the combination produces a logic High (H)
asaresult.IfORisselected,atleastoneofthedened
level conditions must be met. The last item in this menu is
the option TRIGGER ON. Use the soft menu key to select
TRUE or FALSE. This allows you to preselect whether the
trigger will be generated at the beginning (TRUE) or the
end of the logic condition (FALSE).
After selecting the desired set of conditions, you can use
the FILTER key
36
for additional settings. A soft menu will
open allowing you to add a time limit to the TRIGGER ON
option (this menu shows the condition selected in the
SOURCE menu). Press the top soft menu key DURATION
to add a time limit. This option compares the duration of
the output signal for the combination of the logic condi-
tions to the set duration ti. If the duration is identical or not
identical,youcansetthedeviation∆t.Iftiswithinthese
parameters, the trigger condition has been met. The menu
eldbelowallowstheselectionofthecomparisoncriteria.
The following criteria are available:
❙ t
i
≠ t: The duration of the applied bit pattern which will
generatethetriggerisunequaltotheadjustablereference
time.
❙ t
i
= t: The duration of the applied bit pattern which will
generatethetriggerisequaltotheadjustablereference
time.
You may test all settings in the logic trigger without any active
logic probes HO3508 connected.
❙ t
i
< t: The duration of the applied bit pattern which will
generatethetriggerislessthantheadjustablereference
time
❙ t
i
> t: The duration of the applied bit pattern which will
generatethetriggerisgreaterthantheadjustable
reference time.
❙ t
1
<t
i
<t
2
: The pulse width ti which will generate the trigger
islessthantheadjustablereferancetimet
2
and greater
thantheadjustablereference time t
1
.
❙ not(t
1
<t
i
<t
2
): The pulse width which will generate the
triggerisgreaterthantheadjustablereference time t
2
and
lessthantheadjustablereference time t
1
.
❙ Timeout: Triggers if the combination is still valid after
timet.Timetdenesthetrigger time limit for the timeout.
As with the pulse trigger, for t
i
≠tort
i
= t you can set a
reference time with the soft menu key TIME and the
universal knob. Selecting the soft menu item DEVIATION
allows you to use the universal knob and KEYPAD key in
theCURSOR/MENUcontrolpaneltosetthedeviation∆t
whichdenesthetolerancebetweensetreference time t
and valid and real pulse width t
i
(permissible tolerance
range)..
To change the threshold values for the logic states “one”
and “zero”, it is necessary to use settings in the channel
menu (MENU key in the VERTICAL section). Select the
POD
24
). If logic mode is already activated, the digital
channels will be displayed in the channel display section
of the display (framed and marked with “POD:xxxV“).
Pressing the MENU key
21
in the VERTICAL section allows
youtoactivateoneofvepredenedlogiclevels.Threeof
thesearexedforTTL,CMOSandECL.Afterpressingthe
respective menu item, two customized logic levels may
be set from –2 V to 8 V (USER1 / USER2) with the universal
knob or the KEYPAD key in the CURSOR/MENU section.
The soft menu key SET TO DEFAULT POS. & SIZE activates
the display for all digital channels of the selected group by
using default values for the vertical position and size. You
mayalsodenethenameforthecurrentsignalbyusing
thesoftmenuNAME.Alibraryprovidesalistofpredened
names. The name can be activated, deactivated or edited.
Fig. 6.3: Logic channels’ settings display