21
In TRIG ON INTG mode, continuous measurements from a power detector are
integrated and compared against a programmable value. The units of the
programmable value are Joules. If the calculated integral is less than the
specified value, then the trigger output is active. If the calculated integral
exceeds the specified value, then the trigger output becomes inactive. The
TRIG ON INTG trigger is a shift in level rather than a pulse.
If both channels are sampling when this function is initiated, the time lag
between subsequent triggers is less than 700
µ
sec. If a R/S A or R/S B is
initiated twice, then the separation between TTL OUTPUTS is relative to the
RUN command initialization, giving a time lag up to one sample period be-
tween channel triggers (depending on sample frequency chosen).
The polarity of the trigger output is programmable as active high or active
low. If the polarity is active high then the output will idle low. If the polarity is
active low then the line will idle high.
Table 14 – TRIGGER OUT Operations.
Menu Function
Keypad Commands
Associated Remote Commands
TRIGGER OUT
Edit
TRIG ON CMPLT
TRIGOUT, TRIGOUT?
TRIG AT FREQ
TRIG ON LEVEL
TRIG ON INTG
TRIG OUT OFF
TRIG POLARITY
Edit
ACTIVE
HI, LO
TRIGOUTPOL, TRIGOUTPOL?
TRIGGER FREQ
Edit
FREQ=
ddd.ddd
Hz TRIGOUTFREQ, TRIGOUTFREQ?
TRIGGER LEVEL
Edit LVL=
d.dddE
±
dd
W*
TRIGOUTLVL, TRIGOUTLVL?
TRIGGER INTG
Edit INTG=
d.dddE
±
dd
J
TRIGOUTINTG, TRIGOUTINTG?
*Displayed units may be W or J depending upon the detector in use.
2.4.9
Trigger Input
The Model 2835-C’s rear panel TTL external trigger input can be enabled or
disabled, Section 2.3.17, and have its edge polarity set. The edge polarity is
accessed via the EXT TRIGGER IN menu function and can be set to rising or
falling edge triggering.
The external trigger affects both channels and, like the R/S key, acts like an
acquisition trigger when in SNGL modes and acts like a toggled acquisition gate
when in CONT modes. In Peak-to-Peak or Pulse acquisition modes the external
trigger (and R/S key) act to enable single or continuous acquisition rather than
forcing an acquisition to occur at the moment the trigger (or keypress) occurs.
The external trigger pulse width must be
≥
200 ns. In DC SNGL mode, the
delay from the trigger input going active to the start of the A/D conversion is
<80
µ
s. In SNGL PULSE and P-P SNGL modes, the delay from the trigger input
going active to the meter becoming armed to capture the next PULSE or P-P
pair is <70
µ
s.
Table 15 – EXT TRIGGER IN Operations.
Menu Function
Keypad Commands
Associated Remote Commands
EXT TRIGGER IN
Edit
RISING,
EXTEDGE, EXTEDGE?, EXT,
FALLING
EDGE
EXT?
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