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iupigt \j
7.2
{RANGE}
>
>
Remote command
is DG/. Refer
to Chapter
4,
Section 6. 16.
The voltage
DVM
may either be
set for [auto] or any one of four fixed
input
ranges
may be
selected; [200mVj,
[2V], [20V] or
[50V].
Autoranging allows
an
input range in
keeping
with the measured voltage
to
be
selected automatically.
The current
DVM has an input
voltage range of 200mV. Various
ranges of
cell
current
are provided
for by a choice of
standard resistor values. (See Section
2.1.)
7.3
{TRIGGER}
>
>
Remote
command is TR7. Refer
to Chapter
4,
Section 6.16.
Measurements
may be triggered in
any one of four ways, single,
recycled,
external or
sweep synchronized,
as described below.
(single]
When
single measurement
triggering
is selected,
pressing the DVM
RUN
action
key causes
a single set of measurements
to be started
(within
approximately
30ms). Single
measurement triggering is always
selected on
initialization, e.g. on power
up or after RECALL is
used.
[recycle]
When
recycled
measurement triggering
is selected, pressing the DVM
RUN
action key
causes the DVMs
to make measurements continuously
at a reading
rate corresponding to
the DVM
precision selected. Pressing DVM
RUN again
causes recycled
measurements
to be halted.
[external]
External
measurement.
A single measurement
is performed whenever
a
triggering pulse is received
via
the BNC connector on the rear panel
of the
SI
1287
(labelled
TRIGGER).
The trigger pulse may
be a TTL pulse, or a short
circuit.
The maximum
triggering
pulse frequency permitted
depends on the precision
selected
and on
how many voltages
each of the two DVMs must measure
per
reading
cycle. This, however,
depends on what parameters have
been selected
for PARI,
PAR2
and the left and right display
windows.
The highest
maximum triggering
rate occurs when only
one voltage is
being
measured
and equals
the appropriate reading
rate given in section 7.
1 .
E.g.
with
3x9s
selected
PAR1=PAR2==ARE,
and TIME or ’blank’ (which
do not involve
DVMs)
in each display window,
the triggering rate
can be upto 30Hz.
The lowest maximum
triggering rate
occurs when four different voltages
must
be measured
per cycle, which is very
often required in practice.
In this case the
rate
is quartered. E.g. with 3x9s
selected
PARI“RE
1,
PAR2-RE2,
and
displays set
to
ARE
and CE, the triggering
rate is only 7Hz maximum.
Another slowing
factor might
apply; whether or not
the RS232 or GP1B
ports
are
in use. This further
reduces the maximum
possible triggering rate,
by an
amount dependent
on the particular
configuration and peripherals
being used.
Maximum rates
for specific
set-ups must be determined
by the user.
3.18
JWS /
S1
1 287 User
Guide / issue AF
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