5.b PEAK CAPTURE
During setup, a 3500 Series instrument can be placed in either PEAK CAPTURE
or TRACK/HOLD mode, as follows:
1. Enter SETUP MODE by pressing the SETUP button and entering the current
security code, if necessary (as explained in Section 3.a.1).
2. Press the PEAK/TRACK button. The current button mode will be displayed:
either “P” (for PEAK CAPTURE) or “H” (for TRACK/ HOLD). To toggle between
the two settings, simply press the top or bottom segment of the displayed let-
ter.
3. When the desired mode letter is displayed, you can exit SETUP MODE by
pressing the SETUP button once again. For a description of 3500
TRACK/HOLD operation, see Section 5.e.
When a 3500 instrument is in PEAK CAPTURE mode, you can control the peak-
capture function in any one of three ways:
1. By the front-panel PEAK/TRACK button (WHEN THE "PEAK" TERMINAL OF
THE REAR LOGIC I/O CONNECTOR IS AT "LOGIC 0"). Pressing this button
once will place the unit in "+PEAK" MODE, if the "PEAK" terminal is disconnect-
ed (i.e., at "Logic 0").* Pressing the button once more will return the unit to
"TRACK" MODE.
2. By a PEAK (PEK) command applied via the RS-232/485 Interface (WHEN THE
"PEAK" TERMINAL OF THE REAR LOGIC I/O CONNECTOR IS AT "LOGIC 0"). A
command of
PEK=ON [CMT]
will place the unit in "+PEAK" MODE, if the "PEAK" terminal is disconnected
(i.e., at "Logic 0").* A command of
PEK=OFF [CMT]
will return the unit to "TRACK" MODE.
3. By a LOGIC-STATE TRANSITION at the "PEAK" terminal of the rear Logic I/O
Connector. Thus, a transition from Logic 0 to Logic 1 will place the unit in
"+PEAK" MODE, while a transition from Logic 1 to Logic 0 will return it to
"TRACK" MODE, regardless of the last-entered PEAK (PEK) command or the
current state of the PEAK/TRACK button.
Fig. 22 shows the capture and hold of successively higher-valued signal maxima,
after entering the "+PEAK" MODE at time t
1
. Until time t
1
, the "live" data reading
had been continuously "tracking" the analog input. After time t
1
, it continuously
reports the highest input-signal value perceived since "+PEAK" last began. From
time t
1
to time t
2
, the input is continuously rising, and so the reading appears to be
continuing to track it. At time t
2
, however, the input signal reaches its first true
maximum since time t
1
. The instrument "captures" this "positive" peak (P
1
), hold-
ing it as a constant until time t
3
, when a yet higher input value is detected, and the
reading begins once more to track the input upwards to a yet higher peak (P
2
).
5.3
RUN-TIME OPERATION
5
5.b PEAK CAPTURE
* When the "PEAK" terminal is connected to GROUND (i.e., at the "Logic 1" level), both the
PEAK/TRACK button and the PEAK (PEK) command are disabled.
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