Table 1. Connection Accessories and Cables
Connector
Type
Accessory
Accessory
Description
Cable
Cable
Description
MIO
NI SCB-68A
(782536-01)
A 68-pin,
shielded I/O
connector
block
NI SHC68-68-RMIO
(189588-01, 1 meter) or
(189588-02, 2 meter)
A shielded,
68-conductor
cable
DIO
NI SCB-68 HSDIO
(782914-01)
A 68-pin,
shielded
high-speed
digital
connector
block
NI SHC68-C68-RDIO2
(156166-01, 1 meter) or
(156166-02, 2 meter)
A shielded,
digital I/O
68-conductor
cable
Analog Input
The NI USB-7855R provides connections for eight AI channels. Each channel has an AI+ pin,
AI- pin, and AIGND pin to which you can connect both single-ended or differential voltage
signals. Use the AISENSE pin to connect non-referenced single-ended signals.
Connecting Single-Ended Voltage Signals
To connect referenced single-ended voltage signals to the NI USB-7855R, you must connect
the voltage ground signal to AI GND in order to keep the common-mode voltage in the
specified range, as shown in Figure 3.
Figure 3. Connecting Referenced Single-Ended Signals to the NI USB-7855R
PGIA
ADC
AI+
NI USB-7855R
Connection
Accessory
AISENSE
AIGND
V
1
+
–
Overvoltage
Protection
AI–
Overvoltage
Protection
Overvoltage
Protection
To connect non-referenced single-ended voltage signals to the NI USB-7855R, you must
connect the voltage ground signal to AI SENSE in order to keep the common-mode voltage in
the specified range, as shown in Figure 4.
4 | NI USB-7855R User Manual | ni.com
