Keithley 3730

Series 3700
System Switch/Multimeter User's Manual Section 5: Ba
sic Digital Multimeter (DMM) Operation
Document Number: 3700S
-900-01 Rev. A / August 2007 5-
31
Figure 5-20: Simplified normal four-wire open lead detection schematic
ISOUR open voltage
1through 1M ranges: A hardware detector is used to detect an open input lead. The
hardware detector uses a comparator circuit to monitor the voltage on the ohm I
SOUR
V
OPEN-HI-LEAD
terminal.
 For the lower ohms ranges (1, 10, and 10k), open circuit voltage on the ohm I
SOUR
V
OPEN-HI-LEAD
terminal is >7.1V.
 For the higher ohms ranges (100kthrough 1M), open circuit voltage on the ohm I
SOUR
V
OPEN-HI-LEAD
terminal is >12.8V.
When an input lead (HI or LO) is open, as shown, voltage rises to the open-circuit level, then the
A/D will abort in <100sec and the “Overflow” message is displayed.
VMEAS open voltage
If either Input Sense HI or Sense LO V
MEAS
is outside the enclosed table voltages, the A/D will
abort in <100sec and return an overflow reading.
Range
V
MEAS
SHI or SLO
High Limit
Open Lead
Detection
V
MEAS
SHI or SLO
Low Limit Open
Lead Detection
1
-100
> 128mV
< -10mV
1k
-100k
> 1.28V
<
-100mV
1M

> 12.8V
<
-1.0V