Reference Thermistor Connections And Operations - HP VXI E1476A User's Manual And Programming Manual

Reference
Thermistor
Connections and
Operations
Thermistor Excitation
Sources
Caution
Figure 2-10. Connecting Three Thermistors on a Single Panel
Chapter 2
The HP E1586 Terminal Panel's three thermistors are located next to the
channel 3 terminal block, between channels 11 and 16, and next to channel
24 (see Figure 2-9 on page 56).
The excitation is usually supplied by an externally connected multimeter or
voltmeter, like the HP E1326/E1411 5½-Digit Multimeter. When using an
E1326/E1411, the excitation is available on the Terminal Panel's terminals
labeled HI-I and LO-I. The HP E1326/E1411 generates this excitation using
the 2-wire or 4-wire Ohms measurement functions
If using a single HP E1326/E1411 Multimeter to supply the
excitation for multiple HP E1586A Terminal Panels, the
resultant voltage sum of the voltages developed across the
Thermistors could exceed the compliance voltage of the
Multimeter. This is especially true if attempting to excite all
three Thermistors on the Terminal Panels.
The following shows how to connect the thermistors to the current source on
the Analog Bus.
Connecting One Terminal Panel for Reference Temperature
Measurements
In this configuration, a single Terminal Panel is used to provide up to 32
channels for temperature measurements. This provides the excitation current
to all three on-board thermistors on the Terminal Panel. Figure 2-10 shows
the connection for a single Terminal Panel.
Connects All
Thermistors
One HP E1586 Terminal Panel
using All Thermistors
HP E1476A Switchbox Application Examples 57