5: Basic Digital Multimeter (DMM) Operation Series 3700 System Switch/Multimeter
-32 Document Number: 3700S-900-
Calculated measurement open voltage
A calculated measurement, which exceed 120% of the range, will return an overflow reading.
dmm.opendetector open voltage
With dmm.opendetector = dmm.ON, a separate -1.5 A I
OPENLEAD
SHI and a separate SLO current
source, will pulse on and off before the start of each measurement while I
SOUR
remains enabled.
The A/D will monitor SHI for 2msec then switch to SLO for an additional 2msec. During either
phase, if the input voltage exceeds the above table, the A/D will abort in <100sec and return an
overflow reading. If there are no open leads detected during the I
OPENLEAD
phase, the I
OPENLEAD
is
disabled and standard 4-wire is enabled.
V
MEAS
with open input:
If Sense HI is disconnected, V
MEAS
will droop less than -1V, causing an A/D overflow.
V
MEAS
with valid connections:
For valid connections, INPUT Sense HI, V
MEAS
, will dip during the 4msec I
OPENLEAD
phase. The
amount of the voltage dip is the sum of I
OPENLEAD
and the range I
SOUR
and R
DUT
load. For example, if
measuring a 100k on the 100k range, the V
MEAS
across the 100k will be 0.85V (10 A -
1.5A) x 100K during I
OPENLEAD
and 1V during measurement phase.
The tables below notes timing with dmm.opendetector = dmm.ON:
SHI and
SLO
IOPENLEAD
Phase
(msec)1
-
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