Chapter 3
Signal Connections
©
National Instruments Corporation
3-3
Front Signal Connector Signal Descriptions
Analog Input Signal Connections
The signal terminals for the positive input channels are found in Figure 3-1
column C. The signal terminal for each corresponding negative input
channel is found in Figure 3-1 column B. Each input pair goes to a separate
filter and amplifier that is multiplexed to the module output buffer as shown
in Figure 5-1.
The differential input signal range of an SCXI-1104/C module input
channel is 30 VAC
rms
,
±
42 VAC
peak
, and
±
60 VDC. This differential input
range is the maximum measurable voltage difference between the positive
and negative channel inputs. The common-mode input signal range of an
SCXI-1104/C module input channel is
±
60 VDC with respect to the chassis
ground. This common-mode input range for either positive or negative
channel input terminal is the maximum input voltage that results in a valid
measurement.
Subject to the limits stated above, you can connect either floating or
ground-referenced signal sources to the SCXI-1104/C input channels
without using bias resistors.
Cautions
Exceeding the input damage level (
±
42 VAC
peak
or 60 VDC between input
channels and chassis ground) can damage the SCXI-1104/C module, the SCXIbus, and the
DAQ device. National Instruments is not liable for any damage or injuries resulting from
such signal connections.
Applying a voltage greater than
±
42 VAC
peak
or 60 VDC to the SCXI-1104/C is an
electrical shock hazard. National Instruments is not liable for any damages or injuries
resulting from such voltage application.
Pin
Signal Name
Description
A1
+5 V
+5 VDC Source
A2, A5, A16, A24,
A32
CGND
Chassis Ground—Tied to the SCXI chassis.
A3, A4
RSVD
Reserved
B1–B32
CH31– through CH0–
Negative Input Channels—Negative side of differential input
channels.
C1–C32
CH31+ through CH0+
Positive Input Channels—Positive side of differential input channels.
All other pins are not connected.
