National Instruments PXIe-7861, NI PXIe-7861 User Manual

USER MANUAL

NI PXIe-7861

R Series Reconfigurable I/O Module (AI, AO, DIO) for PXI Express,
16 AI, 8 AO, 32 DIO, 1 MS/s AIO, 512 MB DRAM,
Kintex-7 160T FPGA

This document provides compliance, pinout, connectivity, mounting, and power information
for the NI PXIe-7861.

Hardware Overview

The following high-level block diagram represents the NI PXIe-7861.

Figure 1. NI PXIe-7861 Block Diagram

Device

Temperature

NI ASIC

Kintex-7

FPGA

Flash

Memory

DIO

Data/

Address/

Control

Overvoltage

Protection

+5 V

Reference

AO

AO (x8)

DAC

ADC

AI

AI (x8)

INA

DIO (x16)

DDR3 RAM

100 MHz

OSC

Overvoltage

Protection

Overvoltage

Protection

NI PXIe-7861

PXIe Connector

Overvoltage

Protection

+5 V

Reference

ADC

AI (x8)

INA

DIO (x16)

Overvoltage

Protection

AI

DIO

(RMIO)

CONNECTOR 1

(RMIO)

CONNECTOR 0

Pinout

TERMINAL 34

TERMINAL 1

TERMINAL 35

TERMINAL 68

TERMINAL 68

TERMINAL 34

TERMINAL 1

TERMINAL 35

+5V

DIO0

DIO1

DIO2

DIO3

DIO4

DIO5

DIO6

DIO7

DIO9

DIO11

DIO13

DIO15

AO7

AO6

AO5

AO4

AO3

AO2

AO1

AO0

AISENSE0

AI7+

AIGND6

AI6+

AI5+

AIGND4

AI4+

AI3+

AIGND2

AI2+

AI1+

AIGND0

AI0+

+5V

DGND

DGND

DGND

DGND

DGND

DGND

DGND

DGND

DIO8

DIO10

DIO12

DIO14

AOGND7

AOGND6

AOGND5

AOGND4

AOGND3

AOGND2

AOGND1

AOGND0

NC

AI7–

AIGND7

AI6–

AI5–

AIGND5

AI4–

AI3–

AIGND3

AI2–

AI1–

AIGND1

AI0–

68 34

67 33

66 32

65 31

64 30

63 29

62 28

61 27

60 26

59 25

58 24

57 23

56 22

55 21

54 20

53 19

52 18

51 17

50 16

49 15

48 14

47 13

46 12

45 11

44 10

43 9

42 8

41 7

40 6

39 5

38 4

37 3

36 2

35 1

CONNECTOR 0

(RMIO)

+5V

DIO0

DIO1

DIO2

DIO3

DIO4

DIO5

DIO6

DIO7

DIO9

DIO11

DIO13

DIO15

NC

NC

NC

NC

NC

NC

NC

NC

AISENSE1

AI15+

AIGND14

AI14+

AI13+

AIGND12

AI12+

AI11+

AIGND10

AI10+

AI9+

AIGND8

AI8+

+5V

DGND

DGND

DGND

DGND

DGND

DGND

DGND

DGND

DIO8

DIO10

DIO12

DIO14

NC

NC

NC

NC

NC

NC

NC

NC

NC

AI15-

AIGND15

AI14-

AI13-

AIGND13

AI12-

AI11-

AIGND11

AI10-

AI9-

AIGND9

AI8-

68 34

67 33

66 32

65 31

64 30

63 29

62 28

61 27

60 26

59 25

58 24

57 23

56 22

55 21

54 20

53 19

52 18

51 17

50 16

49 15

48 14

47 13

46 12

45 11

44 10

43 9

42 8

41 7

40 6

39 5

38 4

37 3

36 2

35 1

CONNECTOR 1

(RMIO)

Table 1. NI PXIe-7861 Signal Descriptions

Signal Description

AI+ Positive analog input signal connection

AI- Negative analog input signal connection

2 | ni.com | NI PXIe-7861 User Manual

Table 1. NI PXIe-7861 Signal Descriptions (Continued)

Signal Description

AISENSE Reference connection for NRSE measurements

AIGND Ground reference for the analog input signal

AO Analog output signal connection

AOGND Ground reference for the analog output signal

DIO Digital input/output signal connection

DGND Ground reference for the digital signal

GND Ground connection

Supply (+5 V

out

) 5 V power output connection for external devices

NC No connection

The NI PXIe-7861 is protected from overvoltage and overcurrent conditions.

Note Refer to the NI PXIe-7861 Specifications, available at ni.com/manuals for

more information.

Note The pinout label on the lid of the SCB-68A accessory is incompatible with

the NI PXIe-7861. Refer to the NI 78xxR Pinout Labels for the SCB-68A, available
at ni.com/manuals for the compatible pinout labels.

Connectivity Options

Use the following connection accessories and cables to access the signals on the I/O
connectors.

Table 2. Connection Accessories and Cables

Connector Type Accessory Description NI Part Number

RMIO

NI SCB-68A

Noise Rejecting, Shielded I/O
Connector Block

782536-01

NI SHC68-68­RMIO

RMIO Shielded Cable, 68 pin D­Type to 68 pin VHDCI (1 m)

189588-01

RMIO Shielded Cable, 68 pin D­Type to 68 pin VHDCI (2 m)

189588-02

NI PXIe-7861 User Manual | © National Instruments | 3

Analog Input

The NI PXIe-7861 provides connections for 16 AI channels. Each channel has an AI+ pin, AI­pin, 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 PXIe-7861, you must connect the
voltage ground signal to AI GND in order to keep the common-mode voltage in the specified
range.

Figure 2. Connecting Referenced Single-Ended Signals to the NI PXIe-7861

PGIA

ADC

AI+

NI PXIe-7861

Connection

Accessory

AISENSE

AIGND

V

1

+

–

Overvoltage

Protection

AI–

Overvoltage

Protection

Overvoltage

Protection

To connect non-referenced single-ended voltage signals to the NI PXIe-7861, you must
connect the voltage ground signal to AI SENSE in order to keep the common-mode voltage in
the specified range.

Figure 3. Connecting Non-Referenced Single-Ended Signals to the NI PXIe-7861

PGIA

ADC

AI+

NI PXIe-7861

Connection

Accessory

AISENSE

AIGND

V

cm

V

1

+

–

+

–

Overvoltage

Protection

AI–

Overvoltage

Protection

Overvoltage

Protection

4 | ni.com | NI PXIe-7861 User Manual

Connecting Differential Voltage Signals

You can connect grounded or floating differential signal sources to the NI PXIe-7861. Connect
the positive voltage signal to the AI+ and the negative voltage signal to AI-. To connect
grounded differential signals to the NI PXIe-7861, you must also connect the signal reference
to AI GND.

Figure 4. Connecting Grounded Differential Signals to the NI PXIe-7861

PGIA

ADC

AI+

NI PXIe-7861

Connection

Accessory

AISENSE

AIGND

V

cm

V

1

+

–

+

–

Overvoltage

Protection

AI–

Overvoltage

Protection

Overvoltage

Protection

To connect floating differential signals to the NI PXIe-7861, you must connect the negative
and positive signals to AI GND through 1 MΩ resistors to keep the voltage within the
common-mode voltage range. If the voltage source is outside the common-mode voltage
range, the NI PXIe-7861 does not read data accurately.

Figure 5. Connecting Floating Differential Signals to the NI PXIe-7861

PGIA

ADC

AI+

NI PXIe-7861

Connection

Accessory

AISENSE

AIGND

V

1

+

–

Overvoltage

Protection

AI–

Overvoltage

Protection

Overvoltage

Protection

Analog Output

The NI PXIe-7861 provides connections for eight analog output channels. Each channel has an
AO pin and AOGND pin to which you can connect a load.

NI PXIe-7861 User Manual | © National Instruments | 5

Figure 6. Connecting a Load

NI PXIe-7861

Connection

Accessory

AOGND

LOAD

AO

DAC

Digital I/O

The NI PXIe-7861 provides connections for 32 digital input/output (DIO) channels. Connector
0 and Connector 1 each contains 16 low-speed channels that can run up to 10 MHz signal
frequencies. Each connector has a fixed logic level of 3.3 V. You can configure each channel
as input or output.

Figure 7. Connecting to the DIO Channels

NI PXIe-7861

Power

FPGA

Connection

Accessory

DIO0

DIO1

DIO14

DIO15

Connecter 0 (RMIO)

1

Connection

Accessory

DIO0

DIO1

DIO14

DIO15

Connecter 1 (RMIO)

1

2

1. Low-speed signal frequencies up to 10 MHz with logic levels configured as 3.3 V.

2. LED

The DIO channels, which have overvoltage and undervoltage protection as well as over
current protection, connect to the FPGA . Refer to the device specifications on ni.com/manuals
for more information about the maximum voltage and current.

6 | ni.com | NI PXIe-7861 User Manual

When the system powers on, the DIO channels are set as input low with pull-down resistors.
To set another power-on state, you can configure the NI PXIe-7861 to load a VI when the
system powers on. The VI can then set the DIO lines to any power-on state. Visit ni.com/info
and enter RSeries_PowerUpStates to learn more about configuring the power-up states
for the NI PXIe-7861.

All the DIO channels on each connector are routed with a 50 Ω characteristic trace impedance.
Route all external circuitry with a similar impedance to ensure best signal quality. NI
recommends performing signal integrity measurements to test the affect of signal routing with
the cable and connection accessory for your application.

Field Wiring Considerations

Environmental noise can seriously affect the measurement accuracy of the device if you do not
take proper care when running signal wire between signal sources and the device. The
following recommendations mainly apply to AI signal routing to the device, as well as signal
routing in general.

Take the following precautions to minimize noise pickup and maximize measurement
accuracy:

• Use differential AI connections to reject common-mode noise.

• Use individually shielded, twisted-pair wires to connect AI signals to the device. With
this type of wire, the signal attached to the positive and negative inputs are twisted
together and then covered with a shield. You then connect this shield only at one point to
the signal source ground. This kind of connection is required for signals traveling through
areas with large magnetic fields or high electromagnetic interference.

• Route signals to the device carefully. Keep cabling away from noise sources, such as
video monitors and analog signals.

Use the following recommendations for all signal connections to the NI PXIe-7861:

• Separate NI PXIe-7861 signal lines from high-current or high-voltage lines. These lines
can induce currents in or voltages on the NI PXIe-7861 signal lines if they run in parallel
paths at a close distance. To reduce the magnetic coupling between lines, separate them
by a reasonable distance if they run in parallel or run the lines at right angles to each
other.

• Do not run signal lines through conduits that also contain power lines.

• Protect signal lines from magnetic fields caused by electric motors, welding equipment,
breakers, or transformers by running them through special metal conduits.

+5 V Power Source

Use the +5 V terminals on the I/O connector supply +5 V referenced to DGND to power
external circuitry.

Caution Never connect the +5 V power terminals to analog or digital ground or

any other voltage source on the NI PXIe-7861 or any other device. Doing so can

NI PXIe-7861 User Manual | © National Instruments | 7

damage the device and the computer. National Instruments is not liable for damage
resulting from such a connection.

The power rating is 4.75 to 5.1 V DC at 0.5 A per connector.

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378045A-03 March 13, 2018