Chapter 4
Connecting Signals
©
National Instruments Corporation
4-3
Table 4-2.
Signal Descriptions for I/O Connector Pins
Signal Name
Reference
Direction
Description
AIGND
—
—
Analog Input Ground—These pins are the bias current
return point for AI measurements. Refer to Figure 4-3
for recommended connections. All three ground
references—AIGND, AOGND, and DGND—are connected
on the device.
ACH<0..15>
AIGND
Input
Analog Input Channels 0 through 15—Each channel pair,
ACH<
i, i
+8> (
i
= 0..7), can be configured as either one
differential input or two single-ended inputs.
AISENSE
AIGND
Input
Analog Input Sense—This pin serves as the reference node
for any of channels ACH<0..15> in NRSE configuration.
AISENSE must be connected to AIGND directly or to an
external ground reference for single-ended measurements.
Invalid random readings result if AISENSE is left
unconnected when using NRSE mode. Refer to Figure 4-3
for recommended connections.
DAC0OUT
1
AOGND
Output
Analog Channel 0 Output—This pin supplies the voltage
output of AO channel 0.
DAC1OUT
1
AOGND
Output
Analog Channel 1 Output—This pin supplies the voltage
output of AO channel 1.
AOGND
—
—
Analog Output Ground—The AO voltages are referenced to
this node. All three ground references—AIGND, AOGND,
and DGND—are connected on the device.
DGND
—
—
Digital Ground—This pin supplies the reference for the
digital signals at the I/O connector as well as the +5 VDC
supply. All three ground references—AIGND, AOGND,
and DGND—are connected together on the device.
DIO<0..7>
DGND
Input
Output
Digital I/O Signals—DIO6 and 7 can control the up/down
signal of general-purpose counters 0 and 1, respectively.
+5V
DGND
Output
+5 VDC Source—These pins are fused for up to 1 A of
+5 V supply. The fuse is self-resetting.
SCANCLK
DGND
Output
Scan Clock—This pin pulses once for each A/D conversion
in scanning mode when enabled. The low-to-high edge
indicates when the input signal can be removed from the
input or switched to another signal.
EXTSTROBE*
DGND
Output
External Strobe—This output can be toggled under software
control to latch signals or trigger events on external devices.
