External Reset; External Reference; Gate View; Remote Control - Hameg Instruments HM 8123 Manual Del Usario

6.2 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
6.3

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, the
result reset. A new measurement is started when the signal
switches from high to low.
6.4

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
6.5

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.
A: Gate View; B: input signal (10 Hz); Gatetime: 200 ms
, the
and if the
is located on the rear panel.
is located on
is located on the rear panel. The

7 Remote control

7.1

Interfaces

The HM8123 comes with a USB/RS-232 interface, as an option
the IEEE-488 GPIB interface is available. We recommend the
installation ex factory.
RS-232 Interface parameters:
9600 baud, no paritybit, 8 data bits, 1 stop bit
The interface parameters are fixed and cannot be changed.
USB interface
You do not have to change the configuration. If required, the
baud rate can be changed. Connect the HM8123 with your PC
using a USB cable and install the USB drivers like described in
the manual of the USB interface HO820.
GPIB interface
Connect the HM8123 with your PC using a GPIB cable. It is
necessary to set the GPIB adress of the HM8123 to the desired
value. The adress is changed at the interface on the rear panel.
Do this settings only before starting the instrument. It is not
possible when the instrument is running.
7.2

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.)
7.3

Listing of commands

.
pp
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
R e m o t e c o n t r o l
Subject to change without notice
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