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Chapter 3
3.2.2 I/O Connector Signal Description
3.3 Analog Input Connections
USB-4702 supports 8 single-ended/ 4 differential analog inputs. Each
individual input channel is software-selected.
3.3.1 Single-ended Channel Connections
The single-ended input configuration has only one signal wire for each
channel, and the
measured voltage
(Vm) is the voltage of the wire as ref-
erenced against the common ground.
A signal source without a local ground is also called a “floating source”.
It is fairly simple to connect a single-ended channel to a floating signal
source. In this mode, USB-4702 provides a reference ground for external
floating signal sources.
Figure 3.2 shows a single-ended channel connection between a floating
signal source and an input channel on USB-4702.
Table 3.1: I/O Connector Signal Description
Signal Name
Reference Direction
Description
AI<0…7>
AGND
Input
Analog Input Channels 0
through 7.
AO0, AO1
AGND
Output
Analog Input Channels 0 and 1.
AGND
-
-
Analog Ground.
DI<0…7>
DGND
Input
Digital Input Channels 0
through 7.
DO<0…7>
DGND
Output
Digital Output Channels 0
through 7.
DGND
-
-
Digital Ground.
COUNT
DGND
Input
Counter Input.
TRIG
DGND
Input
A/D External Trigger.
+2.5V
AGND
Output
2.5V DC Voltage Output.
+5V
AGND
Output
5V DC Voltage Output.
