Additional Inputs And Outputs; External Arming; External Gate; External Reset - Rohde & Schwarz HAMEG HM8123 Benutzerhandbuch

5 Additional inputs
and outputs
5.1

External Arming

External arming prevents triggering of a measurement by
undesired signals. The ARMED mode is selected by pres-
sing ARMED , the pushbutton will light up. A measure-
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ment can be started either manually by pressing TRIG
or by a signal at the TRIG/ARM input
put connector is located on the front panel. As long as
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there is a low level input signal the counter will not start a
new measurement. A measurement will be started if the
following conditions are all met: the signal at the input
switches from low to high, the trigger conditions selected
are fulfilled. The delay time caused by the arming signal is
50 ns. The measurement will be performed according to
the HM8123 settings. During a measurement any signals
at the TRIG/ARM input
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rement will be started after the measurement time set has
elapsed with the next positive slope at the TRIG/ARM in-
put .
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Arming
Signal
Input A
Number of
periods counted
5.2

External Gate

Ext.-Gate
Signal
Trig.-Level
Input A
Actual
gate time
Number
of counts
A measurement may be started and stopped by a signal
at the gate input TRIG/ARM
the front panel. The gated mode is entered by pressing
GATED , the pushbutton will light up. As long as there is
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a low level at this input no measurement will be started. A
measurement is started by a low to high transition at the
TRIG/ARM input and if the trigger conditions are met.
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. The TRIG/ARM in-
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will be ignored. A new measu-
Measurement time
. This input is located on
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The measurement will be stopped by a high to low tran-
sition at the input. This signal is of higher priority than the
gate time selected. The signal at the TRIG/ARM input
have to be within the range of 50 ns to 10 s. The effective
gate time can not be shorter than 20 µs.
5.3

External Reset

The RESET BNC connector
A high level at this input is identical to pressing the RESET
pushbutton : the current measurement will be halted,
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the result reset. A new measurement is started when the
signal switches from high to low.
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5.4

External Reference

The external reference 10 MHz BNC connector
ted on the rear panel. An external 10 MHz reference may
be conected to this input. The external refrence has to be
selected in the menu (refer to paragraph 4: Menu). This re-
ference signal must have an accuracy of at least ±20 ppm
and an amplitude of 2 V
5.5

Gate View

The BNC connector GATE
The gate open signal is available here e.g. for scope dis-
play. Due to the start sync time this signal will be longer
than the measurement time selected.
A: Gate View; B: input signal (10 Hz); Gate time: 200 ms

Additional inputs and outputs

is located on the rear panel.
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37
.
pp
is located on the rear panel.
32
32
is loca-
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