User`s manual

Connecting Input Signals
This section contains guidelines on connecting input signals to the
multimeter and shows the connections required to make the following
measurements:
• DC and AC RMS Voltage
• 2-Wire Resistance (including thermistors and RTDs)
• 4-Wire Resistance (including thermistors and RTDs)
• Thermocouples
Note Refer to the HP E1355A - E1358A Strain Gage Multiplexers User’s Manual
for information on connecting strain gages.
Wiring
Considerations
To ensure accurate measurements, input signals should be connected to the
multimeter (via its rear terminals or a multiplexer) using a shielded
twisted-pair cable. Twisted-pair cables reduce magnetic (inductive) noise in
the measurement circuit. The shield reduces electrical (capacitive) noise.
Connecting the
COM Lead
To prevent the HI and LO terminals from floating from the COM terminal
and causing erratic overload readings, the COM terminal must be connected
to the signal source. If a shielded cable is used, connect one end of the
cable shield to the LO lead at the signal source, and connect the other end of
the cable shield to the COM (or guard) terminal. If a shielded cable is not
used, connect a COM (guard) lead with the LO lead AT THE SIGNAL
SOURCE. These connections (Figure 2-11), apply to measurement using
the rear terminals or multiplexers.
WARNING The HI, LO, COM, HI terminals on the multimeter faceplate are
internally connected to the analog bus port. Thus, signals on
the analog bus (from a multiplexer) appear on the faceplate
terminals and vice versa.
Figure 2-11. Connecting the COM Lead
32 Configuring the HP E1326B/E1411B Multimeter Chapter 2