Additional Inputs And Outputs; External Arming; External Gate; External Reset - Hameg HM8123 User Manual

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-
28
ment can be started either manually by pressing TRIG
or by a signal at the TRIG/ARM input
The TRIG/ARM input connector
panel. As long as there is a low level input signal the coun-
ter 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 conditi-
ons selected are fulfilled. The delay time caused by the ar-
ming signal is 50 ns. The measurement will be performed
according to the HM8123 settings. During a measurement
any signals at the TRIG/ARM input
new measurement will be started after the measurement
time set has elapsed with the next positive slope at the
TRIG/ARM input 32 .
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 sig-
nal at the gate input TRIG/ARM
on the front panel. The gated mode is entered by pressing
GATED 30 , the pushbutton will light up. As long as there is
a low level at this input no measurement will be started. A
26
.
32
is located on the front
32
32 will be ignored. A
Measurement time
. This input is located
32
measurement is started by a low to high transition at the
TRIG/ARM input and if the trigger conditions are met.
32
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
: the current measurement will be halted,
pushbutton 25
the result reset. A new measurement is started when the
signal switches from high to low.
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
pp
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.
38
37
.
is located on the rear panel.
32
32
is loca-
25