National Instruments SCXI-1121 - Manual (Page 28)

Chapter 2 Configuration and Installation
SCXI-1121 User Manual 2-12 www.natinst.com
Using the Internal Half-Bridge Completion
Your SCXI-1121 includes half-bridge completion for half-bridge and
quarter-bridge setups. The completion network consists of two
4.5 k
Ω
± 0.05% ratio tolerance resistors with a temperature coefficient of
5 ppm/°C. These resistors are connected in series. To enable the network,
you must set two jumpers for each input/excitation channel pair.
When the completion network is enabled, you cannot access the negative
input of the amplifier, which preserves the overvoltage protection of the
channel. Table 2-9 shows how to enable and disable the completion
network.
Note When using the half-bridge completion network with a quarter-bridge setup, you
must use an extra resistor to complete the bridge. Place this resistor on the terminal block
between the positive input channel and the negative excitation output.
Table 2-9. Completion Network Jumpers
Channel Jumpers Enable Completion
Disable Network
(Factory Setting)
0 W1 and W2
1 W17 and W18
A B
W2
W1
1 2 3
•
•
•
•
• • •
A B
W2
W1
1 2 3
•
•
•
•
• • •
A B
W18
W17
1 2 3
•
•
•
•
• • •
A B
W18
W17
1 2 3
•
•
•
•
• • •