Chapter 2
Configuration and Installation
2-32
ni.com
Terminal Block Signal Connection
Caution
The chassis GND terminals on your terminal block are for grounding high
impedance sources such as a floating source (1 mA maximum). Do
not
use these terminals
as safety earth grounds.
Caution
If high voltages (
≥
42 V
rms
) are present, you must connect the safety earth ground
to the strain-relief tab. This complies with UL 1244 and fully protects against electric shock
when the terminal block is not connected to the chassis. To connect the safety earth ground
to the strain-relief tab, run an earth ground wire in the cable from the signal source to the
terminal block. National Instruments is
not
liable for any damages or injuries resulting
from inadequate safety earth ground connections.
To connect the signal to the terminal block, use the following procedure:
1.
Remove the grounding screw of the top cover.
2.
Snap out the top cover of the shield by placing a screwdriver in the
groove at the bottom of the terminal block.
3.
Slide the signal wires, one at a time, through the front panel
strain-relief opening. You can add padding or insulation if necessary.
4.
Connect the wires to the screw terminals. For thermistor and RTD
connection, follow the procedure stated in the
section earlier in this chapter.
5.
Tighten the larger strain-relief screws.
6.
Snap the top cover back in place.
7.
Reinsert the grounding screw to ensure proper shielding.
8.
Connect the terminal block to the SCXI-1121 front connector as
explained in the
section later in this
chapter.
Table 2-15.
Jumper Settings on the SCXI-1321 Terminal Block
Jumper
Position
Description
W5
MTS mode selected;
factory setting;
parking position
W5
DTS mode selected
•
•
•
•
MTEMP
DTEMP
MTEMP
DTEMP
•
•
•
•