National Instruments pxi terminal block ni tb-2708 Manual De Usuario

You can use the TB-2708 to measure floating and ground-referenced 
analog input signals. To measure floating signal sources, move the switch 
located under the rubber-sealed door on the enclosure cover for the AI 
channel you are using to the ON (floating source) switch position. In the 
floating source switch position, the amplifier negative terminal connects to 
ground through a 5 k

Ω resistor in parallel with a 0.1 μF capacitor. Table 2 

shows the TB-2708 switch configuration options.

It is possible to set the switch on the TB-2708 to either the floating or 
ground-referenced source position to measure ground-referenced signals. 
However, for best results, use the OFF (ground-referenced source) switch 
position to avoid ground loops. Refer to the S Series User Manual for more 
information on measuring floating and ground-referenced signals.

Table 2.  Configuration Summary

Floating Source

Ground-
Referenced Source

+

–

Signal

Source

TB-2708

DAQ Device

(Differential Input

Mode)

AI GND

+
–

+

–

Signal

Source

TB-2708

DAQ Device

(Differential Input

Mode)

AI GND

+
–

+

–

Signal

Source

TB-2708

DAQ Device

(Differential Input

Mode)

+
–

AI GND

+

–

Signal

Source

TB-2708

DAQ Device

(Differential Input

Mode)

AI GND

+
–