Hameg HM504-2, Manual

Page: 37 / 42

35
Subject to change without notice
Adjustments
After calling MAIN MENU > ADJUSTMENT > AUTO
ADJUSTMENT, several menu items are displayed. Each item can
be called and causes an automatic adjustment.
All items are subject to the instrument’s temperature response
under extreme environmental temperature conditions and results
are stored in a non volatile memory. Incorrect adjustment settings
can be caused by component failures as a result of the application
of excessive voltage inputs and therefore cannot be compensated
by the automatic adjustment procedure.
Before starting an automatic adjustment procedure a warm up
time of 20 minutes must be allowed. During these automatic
adjustments there must be no signal applied to any input.
The following items are available:
1. SWEEP START POSITIONS
In Yt (time base) mode the trace start position is affected by time
base setting. The automatic adjustment minimises such effects.
During execution the readout indicates “WORKING”.
2. Y AMP (measuring amplifier CH I and CH II)
Different Y deflection coefficient settings cause minor Y position
changes. Changes higher than ± 0.2 div (5 mV/div to 20 V/div)
become corrected. This value relates on open but screened
inputs.
The automatic adjustment affects both channels. After execution
the readout displays the AUTO ADJUSTMENT MENU.
3. TRIGGER AMP
This adjustment reduces trigger amplifiers dc offset to a minimum.
After completion the AUTO ADJUSTMENT MENU becomes
visible again.
4. X MAG POS
This adjustment coordinates the X-POS control setting range in
unmagnified and magnified (X-MAG. x10) condition.
5. CT X-POS
This adjustment adapts the setting range of the X-POS control
setting in “Component Tester” and Yt (X-MAG. x1) mode.
RS-232 Interface - Remote Control
Safety
Caution:
All terminals of the RS-232 interface are galvanically
connected with the oscilloscope and subsequently with
protective (safety) earth potential.
Measurement on a high level reference potential is not permitted
and endangers operator, oscilloscope, interface and peripheral
devices.
In case of disregard of the safety warnings contained in this
manual,
HAMEG refuses any liability regarding personal injury
and/or damage of equipment.
Operation
The oscilloscope is supplied with a serial interface for control
purposes. The interface connector (9 pole D SUB female) is
located on the rear of the instrument. Via this bidirectional port,
the instrument parameter settings can be transmitted to, or
received from a PC.
RS-232 Cable
The maximum connecting cable length must be less then 3
meters and must contain 9 screened lines connected 1:1. The
oscilloscope RS-232 connection (9 pole D SUB female) is
determined as follows:
Pin
2
Tx data (data from oscilloscope to external device)
3 Rx data (data from external device to oscilloscope)
7 CTS (clear to send)
8 RTS (request to send)
5 Ground (reference potential - connected via the
oscilloscope’s power cord with protective earth)
9 +5 V supply for external device (max. 400 mA).
The maximum voltage swing at pin 2, 3, 7 and 8 is ± 12 Volt.
RS-232 protocol
N-8-2 (no parity bit, 8 data bits, 2 stop bits, RTS/CTS hardware
protocol).
Baud-Rate Setting
After the first POWER UP (switching on of the oscilloscope ) and
the first command SPACE CR (20 hex, 0 Dhex) sent from the PC,
the baud rate is recognized and set automatically between 110
baud and 115200 baud. The oscilloscope is then switched over to
REMOTE control mode. The oscilloscope then transmits the
RETURNCODE: 0 CR LF to the PC . In this status all settings (with
the exception of those functions mentioned under ”Controls and
Readout”) can be controlled via the interface only.
The only ways to quit this status are:
I
Switching the oscilloscope off,
or transmitting the command
I
RM= 0 from the PC to the oscilloscope, or
I
depressing the AUTOSET (LOCAL) pushbutton,
if in unlocked condition (command LK=1... was not sent)
After the remote state has been switched off the RM LED is dark.
Please note:
A minimum time must elapse between the commands RM=1...
(remote on) and RM=0... (remote off) and vice versa. The time
can be calculated with the formula:
t
min
= 2x(1/baud rate) + 60µs.
If at the beginning no SPACE CR command is recognizable, the
oscilloscope pulls the TxD line low for approx. 0.2ms and causes
a break on the PC.
Data Communication
After successfully being set to remote control mode, the
oscilloscope is prepared for command reception.
A CompactDisc with programming examples, a command list
and a program executable under Windows 95, 98, Me, 2000, NT
4.0 (with Service Pack 4 or higher) and XP is part of the delivery.
RS-232 Interface – Remote Control