National Instruments PCIe-7846 User manual

National Instruments PCIe-7846 Manual
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USER MANUAL
NI PCIe-7846
R Series Digital I/O Module for PCI Express, 8 AI, 8 AO, 48 DIO,
500 kS/s AI, Kintex-7 160T FPGA
This document provides compliance, pinout, connectivity, mounting, and power information
for the PCIe-7846.
Hardware Overview
The following high-level block diagram represents the PCIe-7846.
Figure 1. PCIe-7846 Block Diagram
NI ASIC
FPGA
NI PCIe-7846
DIO
Data/
Address/
Control
AO
AO (x8)
ADC AI
AI (x8)
INA
DIO (x16)
DIO (x32)
DDR3 RAM
Kintex-7
DAC
+5 V
Reference
CONNECTOR 1
(DIO)
CONNECTOR 0
(MIO)
Device
Temperature
Flash
Memory
100 MHz
OSC
PCIe Connector
Overvoltage
Protection
Overvoltage
Protection
Overvoltage
Protection
Overvoltage
Protection

Pinout
DIO30
GND
DIO28
GND
DIO26
GND
DIO24
GND
DIO22
GND
DIO20
GND
DIO18
GND
DIO16
GND
DIO14
GND
DIO12
GND
DIO10
GND
DIO8
GND
DIO6
GND
DIO4
GND
DIO2
GND
DIO0
GND
EXTCLKIN
GND
DIO31
DIO29
GND
GND
DIO25
GND
DIO23
GND
DIO27
GND
DIO21
GND
DIO19
GND
DIO17
GND
DIO15
GND
DIO13
GND
DIO11
GND
DIO9
GND
DIO7
GND
DIO5
GND
DIO3
GND
DIO1
GND
GND
GND
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
+5V
DIO0
DIO1
DIO2
DIO3
DIO4
DIO5
DIO6
DIO7
DIO9
DIO11
DIO13
DIO15
AO7
AO6
AO5
AO4
AO3
AO2
AO1
AO0
AISENSE
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 1
(DIO)
CONNECTOR 0
(MIO)
TERMINAL 34
TERMINAL 68
TERMINAL 1
TERMINAL 35
TERMINAL 34
TERMINAL 68
TERMINAL 1
TERMINAL 35
Table 1. PCIe-7846 Signal Descriptions
Signal Description
AI+ Positive analog input signal connection
AI- Negative analog input signal connection
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
2| ni.com | NI PCIe-7846 User Manual

Table 1. PCIe-7846 Signal Descriptions (Continued)
Signal Description
DIO Digital input/output signal connection
DGND Ground reference for the digital signal
EXTCLKIN External clock input source that can be used for source synchronous
acquisitions. The provided clock source must be stable and glitch-free.
GND Ground connection
Supply (+5 Vout) 5 V power output connection for external devices
NC No connection
The PCIe-7846 is protected from overvoltage and overcurrent conditions.
Note Refer to the device specifications, available at ni.com/manuals for more
information.
Analog Input
The PCIe-7846 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 PCIe-7846, 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 PCIe-7846
PGIA ADC
AI+
NI PCIe-7846
Connection
Accessory
AISENSE
AIGND
V1
+
–
Overvoltage
Protection
AI– Overvoltage
Protection
Overvoltage
Protection
NI PCIe-7846 User Manual | © National Instruments | 3

To connect non-referenced single-ended voltage signals to the PCIe-7846, 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 PCIe-7846
PGIA ADC
AI+
NI PCIe-7846
Connection
Accessory
AISENSE
AIGND
Vcm
V1
+
–
+
–
Overvoltage
Protection
AI– Overvoltage
Protection
Overvoltage
Protection
Connecting Differential Voltage Signals
You can connect grounded or floating differential signal sources to the PCIe-7846. Connect the
positive voltage signal to the AI+ and the negative voltage signal to AI-. To connect grounded
differential signals to the PCIe-7846, you must also connect the signal reference to AI GND.
Figure 4. Connecting Grounded Differential Signals to the PCIe-7846
PGIA ADC
AI+
NI PCIe-7846
Connection
Accessory
AISENSE
AIGND
Vcm
V1
+
–
+
–
Overvoltage
Protection
AI– Overvoltage
Protection
Overvoltage
Protection
To connect floating differential signals to the PCIe-7846, 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
PCIe-7846 does not read data accurately.
4| ni.com | NI PCIe-7846 User Manual

Figure 5. Connecting Floating Differential Signals to the PCIe-7846
1 MΩ
Resistor
1 MΩ
Resistor
1 MΩ
Resistor
1 MΩ
Resistor
V1
+
–
PGIA ADC
AI+
NI PCIe-7846
Connection
Accessory
AISENSE
AIGND
Overvoltage
Protection
AI– Overvoltage
Protection
Overvoltage
Protection
Analog Output
The PCIe-7846 provides connections for eight analog output channels. Each channel has an
AO pin and AOGND pin to which you can connect a load.
Figure 6. Connecting a Load
NI PCIe-7846
Connection
Accessory
AOGND
LOAD
AO
DAC
Digital I/O
The NI PCIe-7846 provides connections for 48 digital input/output (DIO) channels. Connector
0 contains 16 low-speed channels that can run up to 10 MHz signal frequencies. Connector 1
contains 32 high-speed DIO channels that can run up to 80 MHz signal frequencies and
support external clock source. Each connector has selectable logic levels that you can
configure as 1.2 V, 1.5 V, 1.8 V, 2.5 V, or 3.3 V. You can configure each channel as input or
output.
NI PCIe-7846 User Manual | © National Instruments | 5

Figure 7. Connecting to the DIO Channels
NI PCIe-7846
Power
FPGA
Connection
Accessory
DIO0
DIO1
DIO14
DIO15
Connecter 0 (MIO)
1
Connection
Accessory
DIO0
DIO1
DIO30
DIO31
Connecter 1 (DIO)
2
3
1. Low-speed signal frequencies up to 10 MHz with logic levels configured as 1.2 V, 1.5 V, 1.8 V, 2.5 V, or
3.3 V.
2. High-speed signal frequencies up to 80 MHz with logic levels configured as 1.2 V, 1.5 V, 1.8 V, 2.5 V, or
3.3 V.
3. LED
The DIO channels have overvoltage and undervoltage protection as well as over current
protection. Refer to the device specifications on ni.com/manuals for more information about
the maximum voltage and current.
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 PCIe-7846 to load a VI when the
system powers on. The VI can then set the DIO lines to any power-on state.
All the high-speed DIO channels on Connector 1 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.
6| ni.com | NI PCIe-7846 User Manual

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 PCIe-7846:
• Separate NI PCIe-7846 signal lines from high-current or high-voltage lines. These lines
can induce currents in or voltages on the NI PCIe-7846 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.
• To minimize signal-to-signal skew within each digital channel, maintain signal lines'
length within 1 inch of difference.
+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 PCIe-7846 or any other device. Doing so can
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.
On-board Flash Memory
The PCIe-7846 includes a flash memory on-board, allowing users to store their FPGA bitfile
in the flash memory with NI MAX. The user FPGA bitfile will be loaded from the flash
memory after a system power cycle. For more information on downloading a bitfile to NI
FPGA target, visit ni.com/info and enter the Info Code dwnbitfile.
Monitoring the Device Temperature
You can monitor the device temperature through the onboard temperature sensor of the
PCIe-7846 using an FPGA I/O Node. After adding an FPGA I/O Node to the block diagram,
NI PCIe-7846 User Manual | © National Instruments | 7

click the element section of the node, and select Device Temperature. The return value is in
increments of 0.25 °C. For more details, refer to the NI PCIe-7846 Reference topic in
LabVIEW Help.
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378050A-03 November 5, 2018