Aim-TTI LD400, Инструкция по эксплуатации

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Analogue Remote Control
Two forms of voltage controlled remote operation are available: External Voltage Control, where
an analogue voltage fully defines the demanded level of the chosen operating mode, and
External TTL Control where an external logic voltage selects between the two levels set as
Level A and Level B. The same rear panel control voltage input is used for both of these modes.
The controlling voltage is applied to the two
CONTROL VOLTAGE
terminals on the rear panel.
Each terminal has an input impedance of nominally 400k
Ω
to the load negative terminal.
A differential line receiver allows common mode voltages up to ±100 Volts. The common mode
rejection is better than –66dB (50mV at 100V); although it is typically much better than this
(-80dB), the effect on the programmed level can be significant. Consideration should also be
given to the return path for the input currents.
Pressing the Extern soft-key on the home screen opens the external selection menu, where
either the knob or the
▲ and ▼ soft-keys can be used to highlight the desired external control
method. Pressing the Enable soft-key switches to the highlighted method; alternatively pressing
either the Back soft-key or Home key returns the instrument to the home screen leaving the level
select unchanged.
To return from external to internal control, use one of the three
LEVEL SELECT
keys.
Remote Voltage Control
When External Voltage Control is enabled, the Ext lamp will illuminate and Ext V will be
displayed in the status line. The internal Level A and Level B parameters no longer have any
effect. The load mode and full scale range can still be changed in the usual way if required. The
Dropout Voltage setting remains active, if it is set above zero.
The
CONTROL VOLTAGE
input has a scaling factor of 4 Volts full-scale. The conversion factors for
each mode and range are:
Operating Range Scale Factor
80 Amps 20 Amps per Volt
8 Amps 2 Amps per Volt
80 Volts 20 Volts per Volt
8 Volts 2 Volts per Volt
400 or 600 Watts 150 Watts per Volt
400 Ohms 100 Ohms per Volt
10 Ohms 2·5 Ohms per Volt
1 A/V (Siemens) 0·25 A/V (Siemens) per Volt
40 A/V (Siemens) 10 A/V (Siemens) per Volt
The slew rate circuit and setting remains in circuit and the required transient wave shape can be
obtained by adjusting these settings in combination with the shape of the signal applied to the
remote input, subject to the transition time limitations of the load circuit.
Remote Level Select
When External TTL Control is enabled, the Ext lamp will illuminate and Ext TTL will be displayed
in the status line. If the external signal applied to the
CONTROL VOLTAGE
input is below the logic
threshold (nom 1·5 V) then the level set by the Level A control is active; if the signal is
above the threshold then the level set by the Level B control applies. Any logic signal (TTL or
other) which crosses the 1·5V threshold is satisfactory. The transitions are defined by the setting
of the slew rate. All parameters can be changed as required in the usual way.