External Gate; External Reset; External Reference; Gate View - Rohde & Schwarz Hameg HM8123 Handbuch

External Gate

A measurement may be started and stopped by a signal at
the gate input TRIG/ARM . This input is located on the front
panel. The gated mode is entered by pressing GATED
pushbutton will light up. As long as there is 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
trigger conditions are met. The measurement will be stopped
by a high to low transition 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.
Ext.-Gate
Signal
Trig.-Level
Input A
Actual
gate time
Number
of counts

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, the
result reset. A new measurement is started when the signal
switches from high to low.

External Reference

The external reference 10 MHz BNC connector
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 Menu). This reference signal must have an
accuracy of at least ±20 ppm and an amplitude of 2 V

Gate View

The BNC connector GATE
gate open signal is available here e.g. for scope display. Due to
the start sync time this signal will be longer than the measu-
rement time selected.
, the
and if the
is located on the rear panel.
is located on
.
pp
is located on the rear panel. The

Remote control

The HM8123 comes with a RS-232 interface, IEEE-488 or
USB are available options. We recommend the installation ex
factory.
Interface parameters:
9600 baud, no paritybit, 8 data bits, 1 stop bit

Setup of the commands

A message to the HM8123 may consist of several commands.
The commands have to be separated by semicolon (;). After
receiving a CR (0x13) the HM8123 will start to work on the
commands received. The commands my contain upper and
lower case characters. The commands will be executed in the
order they were received. Any commands which can not be
executed in the mode selected presently will be ignored (e.g.
the command „Set measurement time" (SMTxxxxx) would be
ignored if the event counting mode was selected.)

Listing of commands

Functions: With these commands the measurement functions
are selected.
FRA Frequency channel A (FREQ A)
FRB Frequency channel B (FREQ B)
FRC Frequency channel C (FREQ C)
PRA Period channel A (PER A)
WDA Pulse width channel A (Width A)
RAB Frequency ratio A/B (A:B)
DTA Duty cycle channel A
TI1 Time interval A to B (TI A to B)
TIA Time interval A to B averaged (TIavg A to B)
PHA Phase A to B (Phase A to B)
RPM rpm measurement channel A (RPM A)
TOT Event counting channel A (TOTAL A)
Control of measurements: With these commands parameters
may be changed.
a) Attenuators
Activates/deactivates the attenuators, corresponds to pushbut-
tons 1 : 10 and
AA0 Attenuator channel A off
AA1 Attenuator channel A 1 : 10
AA2 Attenuator channel A 1 : 100
AB0 Attenuator channel B off
AB1 Attenuator channel B 1 : 10
AB2 Attenuator channel B 1 : 100
b) Slope
Selection of trigger slope, corresponds to pushbutton SLOPE
SA0 Positive slope channel A
SA1 Negative Slope channel A
SB0 Positive slope channel B
SB1 Negative slope channel B
c) Low pass fi lter 50 kHz
Activates/deactivates the low pass fi ler, corresponds to push-
button LP 50 kHz
R e m o t e c o n t r o l
Subject to change without notice
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