NI 6281 Specifications

Device Pinouts

Figure 1. NI PCI/PXI-6281 Pinout


Figure 1. NI USB-6281 Mass Termination Pinout


Figure 3. NI USB-6281 Screw Terminal Pinout


Analog Input

Number of channels

8 differential or 16 single ended

ADC resolution

18 bits

DNL

No missing codes guaranteed

INL

Refer to the AI Absolute Accuracy section

Sample rate

Single channel maximum

625 kS/s

Multichannel maximum (aggregate)

500 kS/s

Minimum

No minimum

Timing accuracy

50 ppm of sample rate

Timing resolution

50 ns

Input coupling

DC

Input range

±0.1 V, ±0.2 V, ±0.5 V, ±1 V, ±2 V, ±5 V, ±10 V

Maximum working voltage for analog inputs (signal + common mode)

±11 V of AI GND

CMRR (DC to 60 Hz)

110 dB

Input impedance
Device on

AI+ to AI GND

>10 GΩ in parallel with 100 pF

AI- to AI GND

>10 GΩ in parallel with 100 pF

Device off

AI+ to AI GND

820 Ω

AI- to AI GND

820 Ω

Input bias current

±100 pA

Crosstalk (at 100 kHz)

Adjacent channels

-75 dB

Non-adjacent channels

-95 dB

Small signal bandwidth (-3 dB)

750 kHz filter off, 40 kHz filter on

Input FIFO size

2,047 samples

Scan list memory

4,095 entries

Data transfers

PCI/PXI

DMA (scatter-gather), interrupts, programmed I/O

USB

USB Signal Stream, programmed I/O

Overvoltage protection for all analog input and sense channels

Device on

±25 V for up to eight AI pins

Device off

±15 V for up to eight AI pins

Input current during overvoltage condition

±20 mA maximum/AI pin

Table 5. Settling Time for Multichannel Measurements
Range Filter Off ±15 ppm of Step (±4 LSB for Full-Scale Step) Filter Off ±4 ppm of Step (±1 LSB for Full-Scale Step) Filter On ±4 ppm of Step (±1 LSB for Full-Scale Step)
±5 V, ±10 V 2 μs 8 μs 50 μs
±0.5 V, ±1 V, ±2 V 2.5 μs 8 μs 50 μs
±0.1 V, ±0.2 V 3 μs 8 μs 50 μs

Typical Performance Graphs

Figure 1. AI Settling Error versus Time for Different Source Impedances


Figure 1. AI Small Signal Bandwidth


Figure 1. AI CMRR


AI Absolute Accuracy

AI Absolute Accuracy (Filter On)

Note Accuracies listed are valid for up to two years from the device external calibration.
Table 5. AI Absolute Accuracy (Filter On)
Nominal Range Positive Full Scale Nominal Range Negative Full Scale Residual Gain Error (ppm of Reading) Residual Offset Error (ppm of Range) Offset Tempco (ppm of Range/°C) Random Noise, σ (μVrms) Absolute Accuracy at Full Scale (μV) Sensitivity (μV)
10 -10 40 8 11 60 980 24
5 -5 45 8 11 30 510 12
2 -2 45 8 13 12 210 4.8
1 -1 55 15 15 7 120 2.8
0.5 -0.5 55 30 20 4 70 1.6
0.2 -0.2 75 45 35 3 39 1.2
0.1 -0.1 120 60 60 2 28 0.8
Note Sensitivity is the smallest voltage change that can be detected. It is a function of noise.

Gain tempco

17 ppm/°C

Reference tempco

1 ppm/°C

INL error

10 ppm of range

AI Absolute Accuracy (Filter Off)

Note Accuracies listed are valid for up to two years from the device external calibration.
Table 5. AI Absolute Accuracy (Filter Off)
Nominal Range Positive Full Scale Nominal Range Negative Full Scale Residual Gain Error (ppm of Reading) Residual Offset Error (ppm of Range) Offset Tempco (ppm of Range/°C) Random Noise, σ (μVrms) Absolute Accuracy at Full Scale (μV) Sensitivity (μV)
10 -10 45 10 11 70 1,050 28.0
5 -5 50 10 11 35 550 14.0
2 -2 50 10 13 15 230 6.0
1 -1 60 17 15 12 130 4.8
0.5 -0.5 60 32 20 10 80 4.0
0.2 -0.2 80 47 35 9 43 3.6
0.1 -0.1 120 62 60 9 31 3.6
Note Sensitivity is the smallest voltage change that can be detected. It is a function of noise.

Gain tempco

17 ppm/°C

Reference tempco

1 ppm/°C

INL error

10 ppm of range

AI Absolute Accuracy Equation

AbsoluteAccuracy = Reading · (GainError) + Range · (OffsetError) + NoiseUncertainty

  • GainError = ResidualAIGainError + GainTempco · (TempChangeFromLastInternalCal) + ReferenceTempco · (TempChangeFromLastExternalCal)
  • OffsetError = ResidualAIOffsetError + OffsetTempco · (TempChangeFromLastInternalCal) + INLError
  • NoiseUncertainty =
    RandomNoise3100
    for a coverage factor of 3 σ and averaging 100 points.

AI Absolute Accuracy Example

Absolute accuracy at full scale on the analog input channels is determined using the following assumptions:

  • TempChangeFromLastExternalCal = 10 °C
  • TempChangeFromLastInternalCal = 1 °C
  • number_of_readings = 100
  • CoverageFactor = 3 σ

For example, on the 10 V range of the Filter On accuracy table, the absolute accuracy at full scale is as follows:

  • GainError = 40 ppm + 17 ppm · 1 + 1 ppm · 10 = 67 ppm
  • OffsetError = 8 ppm + 11 ppm · 1 + 10 ppm = 29 ppm
  • NoiseUncertainty =
    60µV3100
    = 18 µV
  • AbsoluteAccuracy = 10 V · (GainError) + 10 V · (OffsetError) + NoiseUncertainty = 980 µV

Analog Triggers

Number of triggers

1

Source

AI <0..15>, APFI 0

Functions

Start Trigger, Reference Trigger, Pause Trigger, Sample Clock, Convert Clock, Sample Clock Timebase

Source level

AI <0..15>

±Full scale

APFI 0

±10 V

Resolution

10 bits, 1 in 1,024

Modes

Analog edge triggering, analog edge triggering with hysteresis, and analog window triggering

Bandwidth (-3 dB)

AI <0..15>

700 kHz filter off, 40 kHz filter on

APFI 0

5 MHz

Accuracy

±1%

APFI 0 characteristics

Input impedance

10 kΩ

Coupling

DC

Protection, power on

±30 V

Protection, power off

±15 V

Analog Output

Number of channels

2

DAC resolution

16 bits

DNL

±1 LSB

Monotonicity

16 bit guaranteed

Accuracy

Refer to the AO Absolute Accuracy section

Maximum update rate

1 channel

2.86 MS/s

2 channels

2.00 MS/s per channel

Timing accuracy

50 ppm of sample rate

Timing resolution

50 ns

Output range (offset ± reference)

Calibrated ranges

±1 V, ±2 V, ±5 V, ±10 V

Offset sources

0 V, 5 V, APFI 0 , AO <0,1 >[1]1 An AO channel cannot be a reference or offset to itself.

Reference sources

1 V, 5 V, 2 V, 10 V, APFI 0, AO <0,1>[2]2 When the USB Screw Terminal device is powered on, the analog output signal is not defined until after the USB configuration is complete.

Maximum output level

±11 V

Output coupling

DC

Output impedance

0.2 Ω

Output current drive

±5 mA

Overdrive protection

±25 V

Overdrive current

20 mA

Power-on state[3]3 For all USB Screw Terminal devices, when powered on, the analog output signal is not defined until after USB configuration is complete.

±5 mV

Power-on glitch

2.3 V peak for 1.2 s

Output FIFO size

8,191 samples shared among channels used

Data transfers

PCI/PXI

DMA (scatter-gather), interrupts, programmed I/O

USB

USB Signal Stream, programmed I/O

AO waveform modes

Non-periodic waveform, periodic waveform regeneration mode from onboard FIFO, periodic waveform regeneration from host buffer including dynamic update

Settling time, full-scale step, 15 ppm (1 LSB)

3 µs

Slew rate

20 V/µs

Glitch energy at midscale transition, ±10 V range

Magnitude

15 mV

Duration

0.5 µs

External Reference

APFI 0 characteristics

Input impedance

10 kΩ

Coupling

DC

Protection, device on

±30 V

Protection, device off

±15 V

Range

±11 V

Figure 1. AO <0,1> External Reference Bandwidth


AO Absolute Accuracy

Absolute accuracy at full-scale numbers is valid immediately following internal calibration and assumes the device is operating within 10 °C of the last external calibration.

Note Accuracies listed are valid for up to two years from the device external calibration.
Table 5. AO Absolute Accuracy
Nominal Range Positive Full Scale Nominal Range Negative Full Scale Residual Gain Error (ppm of Reading) Gain Tempco (ppm/°C) Residual Offset Error (ppm of Range) Offset Tempco (ppm of Range/°C) Absolute Accuracy at Full Scale (μV)
10 -10 55 15 30 12 1,540
5 -5 60 15 30 17 820
2 -2 65 25 40 30 404
1 -1 85 25 57 50 259

Reference tempco

1 ppm/°C

INL error

32 ppm of range

AO Absolute Accuracy Equation

AbsoluteAccuracy = OutputValue · (GainError) + Range · (OffsetError)

  • GainError = ResidualGainError + GainTempco · (TempChangeFromLastInternalCal) + ReferenceTempco · (TempChangeFromLastExternalCal)
  • OffsetError = ResidualOffsetError + AOOffsetTempco · (TempChangeFromLastInternalCal) + INLError

Digital I/O/PFI

Static Characteristics

Number of channels

24 total, 8 (P0.<0..7>), 16 (PFI <0..7>/P1, PFI <8..15>/P2)

I/O type

5 V TTL/CMOS compatible

Ground reference

D GND

Direction control

Each terminal individually programmable as input or output

Pull-down resistor

50 kΩ typical, 20 kΩ minimum

Input voltage protection

±20 V on up to two pins[4]4 Stresses beyond those listed under Input voltage protection may cause permanent damage to the device.

Waveform Characteristics (Port 0 Only)

Terminals used

Port 0 (P0.<0..7>)

Port/sample size

Up to 8 bits

Waveform generation (DO) FIFO

2,047 samples

Waveform acquisition (DI) FIFO

2,047 samples

DI Sample Clock frequency

PCI/PXI

0 MHz to 10 MHz, system and bus activity dependent

USB

0 MHz to 1 MHz, system and bus activity dependent

DO Sample Clock frequency
PCI/PXI

Regenerate from FIFO

0 MHz to 10 MHz

Streaming from memory

0 MHz to 10 MHz, system and bus activity dependent

USB

Regenerate from FIFO

0 MHz to 10 MHz

Streaming from memory

0 MHz to 1 MHz, system and bus activity dependent

Data transfers

PCI/PXI

DMA (scatter-gather), interrupts, programmed I/O

USB

USB Signal Stream, programmed I/O

DI or DO Sample Clock source[5]5 The digital subsystem does not have its own dedicated internal timing engine. Therefore, a sample clock must be provided from another subsystem on the device or an external source.

Any PFI, RTSI, AI Sample or Convert Clock, AO Sample Clock, Ctr n Internal Output, and many other signals

PFI/Port 1/Port 2 Functionality

Functionality

Static digital input, static digital output, timing input, timing output

Timing output sources

Many AI, AO, counter, DI, DO timing signals

Debounce filter settings

125 ns, 6.425 µs, 2.56 ms, disable; high and low transitions; selectable per input

Recommended Operating Conditions

Level Minimum Maximum
Input high voltage (VIH) 2.2 V 5.25 V
Input low voltage (VIL) 0 V 0.8 V
Output high current (IOH) P0.<0..7> -24 mA
Output high current (IOH) PFI <0..15>/P1/P2 -16 mA
Output low current (IOL) P0.<0..7> 24 mA
Output low current (IOL) PFI <0..15>/P1/P2 16 mA

Electrical Characteristics

Level Minimum Maximum
Positive-going threshold (VT+) 2.2 V
Negative-going threshold (VT-) 0.8 V
Delta VT hystersis (VT+ - VT-) 0.2 V
IIL input low current (Vin = 0 V) -10 µA
IIH input high current (Vin = 5 V) 250 µA

Digital I/O Characteristics

Figure 1. Digital I/O (P0.<0..7>): Ioh versus Voh


Figure 1. Digital I/O (PFI <0..15>/P1/P2): Ioh versus Voh


Figure 1. Digital I/O (P0.<0..7>): Iol versus Vol


Figure 1. Digital I/O (PFI <0..15>/P1/P2): Iol versus Vol


General-Purpose Counters/Timers

Number of counter/timers

2

Resolution

32 bits

Counter measurements

Edge counting, pulse, semi-period, period, two-edge separation

Position measurements

X1, X2, X4 quadrature encoding with Channel Z reloading; two-pulse encoding

Output applications

Pulse, pulse train with dynamic updates, frequency division, equivalent time sampling

Internal base clocks

80 MHz, 20 MHz, 0.1 MHz

External base clock frequency

0 MHz to 20 MHz

Base clock accuracy

50 ppm

Inputs

Gate, Source, HW_Arm, Aux, A, B, Z, Up_Down

Routing options for inputs

Any PFI, RTSI, PXI_TRIG, PXI_STAR, analog trigger, many internal signals

FIFO

2 samples

Data transfers

PCI/PXI

Dedicated scatter-gather DMA controller for each counter/timer; interrupts, programmed I/O

USB

USB Signal Stream, programmed I/O

Frequency Generator

Number of channels

1

Base clocks

10 MHz, 100 kHz

Divisors

1 to 16

Base clock accuracy

50 ppm

Output can be available on any output PFI or RTSI terminal.

Phase-Locked Loop (PLL)

Note PCI/PXI devices only.

Number of PLLs

1

Reference signal

PXI_STAR, PXI_CLK10, RTSI <0..7>

Output of PLL

80 MHz Timebase; other signals derived from 80 MHz Timebase including 20 MHz and 100 kHz Timebases

External Digital Triggers

Source

Any PFI, RTSI, PXI_TRIG, PXI_STAR

Polarity

Software-selectable for most signals

Analog input function

Start Trigger, Reference Trigger, Pause Trigger, Sample Clock, Convert Clock, Sample Clock Timebase

Analog output function

Start Trigger, Pause Trigger, Sample Clock, Sample Clock Timebase

Counter/timer function

Gate, Source, HW_Arm, Aux, A, B, Z, Up_Down

Digital waveform generation (DO) function

Sample Clock

Digital waveform acquisition (DI) function

Sample Clock

Device-to-Device Trigger Bus

PCI

RTSI <0..7>[6]6 In other sections of this document, RTSI refers to RTSI <0..7> for the PCI devices or PXI_TRIG <0..7> for PXI devices.

PXI

PXI_TRIG <0..7>, PXI_STAR

USB source

None

Output selections

10 MHz Clock, frequency generator output, many internal signals

Debounce filter settings

125 ns, 6.425 μs, 2.56 ms, disable; high and low transitions; selectable per input

Bus Interface

PCI/PXI

3.3 V or 5 V signal environment

USB

USB 2.0 Hi-Speed or full-speed[7]7 If you are using an USB M Series device in full-speed mode, device performance will be lower and you will not be able to achieve maximum sample/update rates., [8]8 Operating on a full-speed bus may result in lower performance.

DMA channels (PCI/PXI)

6, can be used for analog input, analog output, digital input, digital output, counter/timer 0, counter/timer 1

USB Signal Stream

4, can be used for analog input, analog output, digital input, digital output, counter/timer 0, counter/timer 1

The PXI device supports one of the following features:
  • May be installed in PXI Express hybrid slots
  • Or, may be used to control SCXI in PXI/SCXI combo chassis
Table 5. PXI/SCXI Combo and PXI Express Chassis Compatibility
M Series Part Number SCXI Control in PXI/SCXI Combo Chassis PXI Express Hybrid Slot Compatible
191501C-03 No Yes
191501A-0x/191501B-0x Yes No

Power Requirements

PCI/PXI
Current draw from bus during no-load condition

+5 V

0.03 A

+3.3 V

0.78 A

+12 V

0.40 A

-12 V

0.06 A

Current draw from bus during AI and AO overvoltage condition

+5 V

0.03 A

+3.3 V

1.26 A

+12 V

0.43 A

-12 V

0.06 A

Note Current draw from bus during no-load condition or AI/AO overvoltage condition does not include P0/PFI/P1/P2 and +5 V terminals.
Caution USB devices must be powered with an NI offered AC adapter or a National Electric Code (NEC) Class 2 DC source that meets the power requirements for the device and has appropriate safety certification marks for country of use.
USB

Power supply requirements

11 to 30 VDC, 20 W, locking or non-locking power jack with 0.080 in. diameter center pin, 5/16-32 thread for locking collars

Power supply fuse

2 A, 250 V

Current Limits

Caution Exceeding the current limits may cause unpredictable behavior by the device and/or PC/chassis.

PCI, +5 V terminal

1 A max

PXI

+5 V terminal

1 A max

P0/PFI/P1/P2 and +5 V terminals combined

2 A max

USB

+5 V terminal

1 A max

P0/PFI/P1/P2 and +5 V terminals combined

2 A max

Note The +5 V terminal on older PCI/PXI board revisions has a self-resetting fuse that opens when current exceeds this specification. Newer revisions have a traditional fuse that opens when current exceeds this specification. This fuse is not customer-replaceable; if the fuse permanently opens, return the device to NI for repair.
Note The +5 V terminal on USB-6281 has a user-replaceable socketed fuse that opens when current exceeds this specification. Refer to the SCB-68 and SCB-68A : DAQ Multifunction I/O Accessory Guide for information about fuse replacement.

Physical Characteristics

Dimensions

PCI printed circuit board

10.6 cm × 15.5 cm(4.2 in. × 6.1 in.)

PXI printed circuit board

Standard 3U PXI

Mass Termination enclosure (includes connectors)

18.8 cm × 17.09 cm × 4.45 cm (7.4 in. × 6.73 in. × 1.75 in.)

Screw Terminal (includes connectors)

26.67 cm × 17.09 cm × 4.45 cm(10.5 in. × 6.73 in. × 1.75 in.)

USB OEM

Refer to the NI USB-622x/625x/628x OEM User Guide

Weight

PCI

158 g (5.6 oz)

PXI

225 g (7.9 oz)

USB Mass Termination

1.04 kg (2 lb4.5 oz)

USB Screw Terminal

1.46 kg (3 lb3.4 oz)

USB OEM

261 g (9.2 oz)

I/O connectors

Mass Termination

1 68-pin SCSI

USB OEM

1 34-pin IDC, 1 50-pin IDC

Screw terminal wiring

16 AWG to 28 AWG

Calibration

Recommended warm-up time

PCI/PXI/PCI Express/PXI Express

15 minutes

USB

30 minutes

Calibration interval

2 years

Maximum Working Voltage

Connect only voltages that are below these limits.

Channel-to-earth

11 V, Measurement Category I

Measurement Category I is for measurements performed on circuits not directly connected to the electrical distribution system referred to as MAINS voltage. MAINS is a hazardous live electrical supply system that powers equipment. This category is for measurements of voltages from specially protected secondary circuits. Such voltage measurements include signal levels, special equipment, limited-energy parts of equipment, circuits powered by regulated low-voltage sources, and electronics.

Caution Do not use for measurements within Categories II, III, or IV.
Note Measurement Categories CAT I and CAT O (Other) are equivalent. These test and measurement circuits are not intended for direct connection to the MAINS building installations of Measurement Categories CAT II, CAT III, or CAT IV.

Environmental

Operating temperature

PCI/PXI

0 ºC to 55 ºC

USB

0 ºC to 45 ºC

Storage temperature

-20 ºC to 70 ºC

Humidity

10% RH to 90% RH, noncondensing

Maximum altitude

2,000 m

Pollution Degree (indoor use only)

2

Indoor use only.

Shock and Vibration (PXI Only)

Operational shock

30 g peak, half-sine, 11 ms pulse (Tested in accordance with IEC 60068-2-27. Test profile developed in accordance with MIL-PRF-28800F.)

Random vibration

Operating

5 Hz to 500 Hz, 0.3 grms

Nonoperating

5 Hz to 500 Hz, 2.4 grms (Tested in accordance with IEC 60068-2-64. Nonoperating test profile exceeds the requirements of MIL-PRF-28800F, Class 3.)

Safety Compliance Standards

This product is designed to meet the requirements of the following electrical equipment safety standards for measurement, control, and laboratory use:

  • IEC 61010-1, EN 61010-1
  • UL 61010-1, CSA C22.2 No. 61010-1
Note For safety certifications, refer to the product label or the Product Certifications and Declarations section.

EMC Standards

This product meets the requirements of the following EMC standards for electrical equipment for measurement, control, and laboratory use:

  • EN 61326-1 (IEC 61326-1): Class A emissions; Basic immunity
  • EN 55011 (CISPR 11): Group 1, Class A emissions
  • EN 55022 (CISPR 22): Class A emissions
  • EN 55024 (CISPR 24): Immunity
  • AS/NZS CISPR 11: Group 1, Class A emissions
  • AS/NZS CISPR 22: Class A emissions
  • FCC 47 CFR Part 15B: Class A emissions
  • ICES-001: Class A emissions
Note In the United States (per FCC 47 CFR), Class A equipment is intended for use in commercial, light-industrial, and heavy-industrial locations. In Europe, Canada, Australia and New Zealand (per CISPR 11) Class A equipment is intended for use only in heavy-industrial locations.
Note Group 1 equipment (per CISPR 11) is any industrial, scientific, or medical equipment that does not intentionally generate radio frequency energy for the treatment of material or inspection/analysis purposes.
Note For EMC declarations and certifications, and additional information, refer to the Product Certifications and Declarations section.

CE Compliance

This product meets the essential requirements of applicable European Directives, as follows:

  • 2014/35/EU; Low-Voltage Directive (safety)
  • 2014/30/EU; Electromagnetic Compatibility Directive (EMC)
  • 2011/65/EU; Restriction of Hazardous Substances (RoHS)

Product Certifications and Declarations

Refer to the product Declaration of Conformity (DoC) for additional regulatory compliance information. To obtain product certifications and the DoC for NI products, visit ni.com/product-certifications, search by model number, and click the appropriate link.

Environmental Management

NI is committed to designing and manufacturing products in an environmentally responsible manner. NI recognizes that eliminating certain hazardous substances from our products is beneficial to the environment and to NI customers.

For additional environmental information, refer to the Engineering a Healthy Planet web page at ni.com/environment. This page contains the environmental regulations and directives with which NI complies, as well as other environmental information not included in this document.

EU and UK Customers

  • Waste Electrical and Electronic Equipment (WEEE)—At the end of the product life cycle, all NI products must be disposed of according to local laws and regulations. For more information about how to recycle NI products in your region, visit ni.com/environment/weee.
  • 电子信息产品污染控制管理办法(中国RoHS)

  • 中国RoHSNI符合中国电子信息产品中限制使用某些有害物质指令(RoHS)。关于NI中国RoHS合规性信息,请登录 ni.com/environment/rohs_china。(For information about China RoHS compliance, go to ni.com/environment/rohs_china.)
  • 1 An AO channel cannot be a reference or offset to itself.

    2 When the USB Screw Terminal device is powered on, the analog output signal is not defined until after the USB configuration is complete.

    3 For all USB Screw Terminal devices, when powered on, the analog output signal is not defined until after USB configuration is complete.

    4 Stresses beyond those listed under Input voltage protection may cause permanent damage to the device.

    5 The digital subsystem does not have its own dedicated internal timing engine. Therefore, a sample clock must be provided from another subsystem on the device or an external source.

    6 In other sections of this document, RTSI refers to RTSI <0..7> for the PCI devices or PXI_TRIG <0..7> for PXI devices.

    7 If you are using an USB M Series device in full-speed mode, device performance will be lower and you will not be able to achieve maximum sample/update rates.

    8 Operating on a full-speed bus may result in lower performance.