Справочник Пользователя для National Instruments pci-6110e-6111e

Chapter 4

Signal Connections

4-10

 National Instruments Corporation

Table 4-3 summarizes the recommended DIFF signal connections and 
includes input examples for both types of signal sources.

A differential connection is one in which the 611X E board analog input 
signal has its own reference signal or signal return path. The 611X E 
channels are always configured in DIFF input mode. The input signal is 
tied to the positive input of the PGIA, and its reference signal, or return, 
is tied to the negative input of the PGIA.

Each differential signal uses two inputs—one for the signal and one for 
its reference signal. 

Differential signal connections reduce picked up noise and increase 
common-mode noise rejection. Differential signal connections also 
allow input signals to float within the common-mode limits of the 
PGIA.

Table 4-3.  Signal Source Types

Input Examples

• Ungrounded Thermocouples

• Signal conditioning with isolated 

outputs

• Battery devices

• Plug-in cards with nonisolated 

outputs

Differential 
(DIFF)

See text for information on bias resistors. 

+

-

+
-

ACH0(+)

ACH0(-)

ACH0GND

V

1

+

-

+
-

ACH0(+)

ACH0(-)

ACH0GND

V

1

PCI_E.book  Page 10  Thursday, June 25, 1998  12:55 PM