NOTES:
1. Leave zero check enabled when connecting or disconnect-
ing input signals, or when changing functions.
2. In V/I ohms, the display will go blank if zero check is
enabled.
3. Zero will automatically be scaled when the instrument is
moved uprange.
4. Do not move the instrument down range after zero-
correcting the instrument. Re-zero the instrument after
moving downrange.
2.11.2 Using Suppression
The suppression mode allows a stored offset value to be sub-
tracted from subsequent readings. When the SUPPRESS but-
ton is pressed, the instrument will trigger a conversion and in-
ternally store the displayed value as a baseline. The SUP-
PRESS LED will illuminate. All subsequent readings will be
the difference between the suppressed value and the actual
signal level.
The baseline maintains its absolute value regardless of range.
For example, if a 1V signal is .suppressed on the 2V range, it
will remain at 1V on the 20V and 2COV ranges. Only one
reading for the presently selected function can be supressed;
the value will be lost if the function is changed except when in
the V/I ohms mode. The instrument can be toggled between
V/I ohms and amps without loosing the stored value.
The suppressed readings can be as small as the resolution of
the instrument will allow, or as large as full range. Some
typical examples include:
Suppressed
Reading
+10.500 v
+2.556 nA
-12.6CihA
Applied
Signal
+18.600 v
+1.8occ IL4
+4.5cnmA
To use suppression, perform the following
1. Cancel suwress if uresentlv enabled
. . . .
Displayed
Value
+g.100 v
-0.7560 nA
+17.1oomA
4. Press the SUPPRESS button. The triggered reading will be
stored at that point. (If suppressing current in V/I ohms,
press SHIFT OHMS 1.
5. Disconnect the supressed signal from the input and connect
the signal to be measured in its place. Subsequent readings
will be the difference between the supressed value and the
applied signal.
6. To return the instrument to the normal mode, press the
SUPPRESS button. The SUPPRESS Light will go off and
the instrument will be taken out of the suppression mode.
The previously stored suppressed value will be cancelled.
NOTES:
1. Using suppress reduces the dynamic range of the measure-
ment. For example, if the suppressed value is -100mV on
the 2COmV range, an input voltage of 1OOmV or more
would overrange the instrument even though input vol-
tages up to 199.99mV are normally within the capabilities
of the 2OOmV range. If the instrument is in the autorange
mode, it will move up range, if necessary.
2. Setting the range lower than the suppressed value will
overrange the display; the instrument will display the
“OL” message under these conditions.
3. To store a new baseline, suppress must first be disabled
and the enabled once again. The new value will be stored
with the first triggered conversion.
4. Do not move the instrument down range when using sup-
press
5. If the instrument is in the V/I ohms when suppress is en-
abled, the displayed resistance value will be supressed
(supression will be cancelled temporarily by going to
amps).
6. To suppress the current in V/I ohms, enter amps and
then enable suppress. Enter V/I ohms in the usual
manner.
2.12 DATA STORAGE
The Model 617 has an internal loo-point data store mode that
can be used to log a series of readings. The fill rate of the data
store can be set to specific intervals by a parameter that is
entered when the storage mode is first enabled. Alternatively,
a special one-shot trigger mode can be used to control the fill
rate from the front panel. Once data is stored, readings can be
easily recalled from the front panel.
2. Select a range and function that is consistent with the an-
ticipated mesurement. If current is to be suppressed in
Minimum and maximum values can also be retained for
V/I ohms, select amps first.
future recall. As long as data store is enabled, maximum and
3. Connect the signal to be supressed to the instrument input.
minimum values are updated with each conversion.
WARNING
Enter the data storage mode as follows:
The voltage on the input terminals may be
larger than the displayed value. For exam-
pie, if a 15OVDC baseline is stored, an ap-
plied voltage of + 176V will result in a dis-
played value of only +25V.
1. Press and hold the DATA STORE ON/OFF button. The
m me u.4 I A 3 I uxc VIY t u-r Duwm.
I ne
instrument will then scroll through the various reading
rill then scroll through the various reading
rates that are listed in Table 2-7. In addition to the con-
: listed in Table 2-7. In addition to the con-
tinuous rate, which stores readings at the conversion rate,
which stores readings at the conversion rate,
five additional intervals from one reading per second to al intervals from one reading per second to
2-27
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