# National Instruments SCXI-1321 User Manual

## Page 9 9

SCXI-1321 Terminal Block Installation Guide

The factory default value of all the nulling resistors on the terminal block
is 39 k

Ω .

Note

These resistors are socketed for easy replacement. These sockets best fit a 1/4 W

To determine the nulling range, use the following formula while referring
to Figures 3 through 5:

where

V

exc

is the excitation voltage (3.3 V or 10 V)

R

d

is either a completion resistor or a second strain-gauge nominal

resistance

R

null

is the nulling resistor value

(range of trim potentiometer + nulling resistor)

R

g

is the nominal strain-gauge resistance value

For example,

V

nulling range

= ±2.56 mV

V

exc

= 3.3 V

R

d

= 120

R

null

= 39 k

R

g

= 120

Table 2. Nulling Resistors and Corresponding Channels

Channel Number

Nulling Resistor

0

R3

1

R5

2

R7

3

R9

V

nulling range

V

exc

2

----------

V

exc

R

d

R

null

R

g

+

(

)

R

null

R

g

R

d

R

null

R

g

+

(

)

+

-----------------------------------------------------------

±

=