National Instruments NI USB-7855R User manual

National Instruments USB-7855 Manual
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USER MANUAL
NI USB-7855R
R Series for USB Multifunction RIO with Kintex-7 70T FPGA
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This document provides compliance, pinout, connectivity, mounting, and power information
for the National Instruments USB-7855R.
Safety Guidelines
Caution Do not operate the NI USB-7855R in a manner not specified in this user
manual. Product misuse can result in a hazard. You can compromise the safety
protection built into the product if the product is damaged in any way. If the product
is damaged, return it to National Instruments for repair.
Electromagnetic Compatibility Guidelines
This product was tested and complies with the regulatory requirements and limits for
electromagnetic compatibility (EMC) as stated in the product specifications. These
requirements and limits are designed to provide reasonable protection against harmful
interference when the product is operated in its intended operational electromagnetic
environment.
This product is intended for use in residential, commercial, and industrial locations. However,
harmful interference may occur in some installations or when the product is connected to a
peripheral device or a test object. To minimize interference with radio and television reception
and prevent unacceptable performance degradation, install and use this product in strict
accordance with the instructions in the product documentation.

Furthermore, any changes or modifications to the product not expressly approved by National
Instruments could void your authority to operate it under your local regulatory rules.
Caution To ensure the specified EMC performance, operate this product only with
shielded cables and accessories.
Caution To ensure the specified EMC performance, you must install the included
snap-on ferrite bead onto the DC power cord of the power supply as described in the
getting started guide.
Hardware Overview
The following high-level block diagram represents the NI USB-7855R.
Figure 1. NI USB-7855R Block Diagram
Device
Temperature
Overvoltage
Protection
Overvoltage
Protection
FPGA
Temperature
40 MHz
OSC
AO (x8)
USB
NI ASICKintex-7
FPGA
NI USB-7855R
Flash
Memory
DIO
+5 V
Reference
DAC AO
ADC AI
CONNECTOR 0
(DIO)
CONNECTOR 1
(MIO)
Data/
Address/
Control
AI (x8)
INA
DIO (x16)
DIO (x32)
Overvoltage
Protection
Overvoltage
Protection
Connecting the NI USB-7855R
The NI USB-7855R provides connections for eight analog input (AI) channels, eight analog
output (AO) channels, and forty-eight digital input/output (DIO) channels, as shown in Figure
2.
2 | NI USB-7855R User Manual | ni.com

Figure 2. NI USB-7855R 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
GND
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 0
(DIO)
CONNECTOR 1
(MIO)
TERMINAL 34
TERMINAL 68
TERMINAL 1
TERMINAL 35
TERMINAL 34
TERMINAL 68
TERMINAL 1
TERMINAL 35
Connectivity Options
Use the following connection accessories and cables to access the signals on the I/O
connectors.
NI USB-7855R User Manual | © National Instruments | 3

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
V1
+
–
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

Figure 4. Connecting Non-Referenced Single-Ended Signals to the NI USB-7855R
PGIA ADC
AI+
NI USB-7855R
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 NI USB-7855R.
Connect the positive voltage signal to the AI+ and the negative voltage signal to AI-. To
connect grounded differential signals to the NI USB-7855R, you must also connect the signal
reference to AI GND.
Figure 5. Connecting Grounded Differential Signals to the NI USB-7855R
PGIA ADC
AI+
NI USB-7855R
Connection
Accessory
AISENSE
AIGND
Vcm
V1
+
–
+
–
Overvoltage
Protection
AI– Overvoltage
Protection
Overvoltage
Protection
To connect floating differential signals to the NI USB-7855R, 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 USB-7855R does not read data accurately.
NI USB-7855R User Manual | © National Instruments | 5

Figure 6. Connecting Floating Differential Signals to the NI USB-7855R
PGIA ADC
AI+
NI USB-7855R
Connection
Accessory
AISENSE
AIGND
V1
+
–
Overvoltage
Protection
AI– Overvoltage
Protection
Overvoltage
Protection
Analog Output
The NI USB-7855R provides connections for eight analog output channels. Each channel has
an AO pin and AOGND pin to which you can connect a load.
Figure 7. Connecting a Load
NI USB-7855R
Connection
Accessory
AOGND
LOAD
AO
DAC
Digital I/O
The NI USB-7855R provides connections for 48 digital input/output (DIO) channels.
Connector 0 contains 32 high-speed DIO channels that can run up to 80 MHz signal
frequencies and Connector 1 contains 16 low-speed channels that can run up to 10 MHz signal
frequencies. 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.
6 | NI USB-7855R User Manual | ni.com

Figure 8. Connecting to the DIO Channels
NI USB-7855R
Power
FPGA
Connection
Accessory
DIO0
DIO1
DIO30
DIO31
Connecter 0 (DIO)
1
Connection
Accessory
DIO0
DIO1
DIO14
DIO15
Connecter 1 (MIO)
2
3
1. 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.
2. 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.
3. LED
The DIO channels connect to the FPGA through buffers, which have overvoltage and
undervoltage protection as well as over current protection. Refer to the NI USB-7855R
Specifications 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 USB-7855R 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 0 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.
NI USB-7855R User Manual | © National Instruments | 7

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 USB-7855R:
• Separate NI USB-7855R signal lines from high-current or high-voltage lines. These lines
can induce currents in or voltages on the NI USB-7855R 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.
Mounting R Series USB Devices
You can use your R Series USB device on a desktop, mount it on a wall, or mount it on a DIN
rail.
Panel or Wall Mounting
Complete the following steps to panel or wall mount your NI USB-7855R. You can purchase
the panel mounting kit at ni.com with part number 781514-01.
1. Use three #8-32 flathead screw to attach the backpanel wall mount to the panel or wall.
Tighten the screw with a #2 Phillips screwdrivers to a torque of 1.1 N · m (10 lb · in.).
2. Place the NI USB-7855R on the backpanel wall mount with the signal wires facing down
and the device bottom sitting on the backpanel wall mount lip.
3. While holding the NI USB-7855R in place, attach the front bracket to the backpanel wall
mount by tightening the two thumbscrews.
8 | NI USB-7855R User Manual | ni.com

Figure 9. Wall or Panel Mounting the NI USB-7855R
DIN Rail Mounting
Complete the following steps to mount your NI USB-7855R. You can purchase a DIN rail
mounting clip at ni.com with part number 781515-01.
1. Fasten the DIN rail clip to the back of the backpanel wall mount using a #1 Phillips
screwdriver and four machine screws. Tighten the screws to a torque of 0.4 N · m (3.6 lb
· in.).
2. Clip the bracket onto the DIN rail as shown.
Figure 10. DIN Rail Clip Parts Locator Diagram
1
2
3
1. DIN Rail Clip
2. DIN Rail Spring
3. DIN Rail
3. Place the NI USB-7855R on the backpanel wall mount with the signal wires facing down
and the device bottom sitting on the backpanel wall mount lip.
4. While holding the NI USB-7855R in place, attach the front bracket to the backpanel wall
mount by tightening the two thumbscrews.
NI USB-7855R User Manual | © National Instruments | 9