USB-6421 and USB-6421 (OEM) Specifications

USB-6421 and USB-6421 (OEM) Specifications

These specifications apply to the USB-6421 and USB-6421 (OEM). Unless the OEM version is specified, USB-6421 refers to both versions.

Revision History

Version Date changed Description
379041D-01 February 2025 Added 1.8 V, 2.5 V, and 3.3 V logic families and analog triggers.
379041C-01 November 2024 Added USB-6421 (OEM).
379041B-01 October 2024 Updated for the NI mioDAQ 24C3 release.
379041A-01 September 2024 Initial release.

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Definitions

Warranted specifications describe the performance of a model under stated operating conditions and are covered by the model warranty.

Characteristics describe values that are relevant to the use of the model under stated operating conditions but are not covered by the model warranty.

  • Typical specifications describe the performance met by a majority of models.
  • Nominal specifications describe an attribute that is based on design, conformance testing, or supplemental testing.

Specifications are Typical unless otherwise noted.

Conditions

Specifications are valid at 25 °C unless otherwise noted.

USB-6421 AI Connector Pinout

Use the pinout to connect to analog input terminals on the USB-6421.

Figure 1. USB-6421 AI Connector Pinout


Table 1. USB-6421 AI Connector Pin Assignments
Pin Signal
1 AI 8
2 AI 9
3 AI 10
4 AI 11
5 AI 12
6 AI 13
7 AI 14
8 AI 15
9 AI GND
10 No connect
11 No connect
12 No connect
13 No connect
14 No connect
15 No connect
16 No connect
17 No connect
18 CHSGND
19 AI 0
20 AI 1
21 AI 2
22 AI 3
23 AI 4
24 AI 5
25 AI 6
26 AI 7
27 NR (AI SENSE)
28 No connect
29 No connect
30 No connect
31 No connect
32 No connect
33 No connect
34 No connect
35 No connect
36 ID 0
Table 2. USB-6421 AI Connector Signal Descriptions
Signal Function Reference Direction Description
AI <0..7> Analog input channels Varies Input

Supports differential or single-ended measurement modes. The default configuration is differential mode.

In differential mode, these channels are the positive input for the differential pair. The negative input of the differential pair is located directly beneath the positive input.

In single-ended mode, each signal is a separate analog input voltage channel. The ground reference in single-ended mode is configurable. In referenced single-ended (RSE) mode, AI GND is the reference for the voltage measurement. In non-referenced single-ended (NRSE) mode, the NR pin is the reference.

Note You can configure the input mode per channel.
AI <8..15> Analog input channels Varies Input

Supports single-ended measurements only. The default configuration is RSE mode. In RSE mode, AI GND is the reference for the voltage measurement. In NRSE mode, the NR pin is the reference.

For differential measurements, refer to the descriptions for AI <0..7>.

AI GND Analog input ground The reference point for single-ended measurements in RSE mode and the bias current return point for differential measurements.

AI GND, AO GND, D GND, and CHSGND are all connected internally.

NR (AI SENSE) AI SENSE for NRSE mode Input The AI SENSE pin is labeled "NR" because it is used when the input terminal is configured to NRSE mode. In NRSE mode, AI SENSE acts as a remote sense of a reference voltage that can be at a different voltage potential than AI GND.
CHSGND Chassis ground Connects directly to the chassis ground of the USB-6421 enclosure. It can be used as a termination point for shielded cables to help improve measurement quality.
ID 0 This feature is not supported yet.

USB-6421 AO/DIO Connector Pinout

Use the pinout to connect to analog output and digital input/output terminals on the USB-6421.

Figure 2. USB-6421 AO/DIO Connector Pinout


Table 3. USB-6421 AO/DIO Connector Pin Assignments
Pin Signal
1 CHSGND
2 AO GND
3 AO GND
4 AO GND
5 AO GND
6 D GND
7 D GND
8 PFI 8/P0.8 (port0/line8)
9 PFI 9/P0.9 (port0/line9)
10 D GND
11 PFI 10/P0.10 (port0/line10)
12 PFI 11/P0.11 (port0/line11)
13 D GND
14 PFI 12/P0.12 (port0/line12)
15 PFI 13/P0.13 (port0/line13)
16 D GND
17 PFI 14/P0.14 (port0/line14)
18 PFI 15/P0.15 (port0/line15)
19 ID 1
20 AO 0
21 AO 1
22 No connect
23 No connect
24 +5 V
25 PFI 0/P0.0 (port0/line0)
26 PFI 1/P0.1 (port0/line1)
27 D GND
28 PFI 2/P0.2 (port0/line2)
29 PFI 3/P0.3 (port0/line3)
30 D GND
31 PFI 4/P0.4 (port0/line4)
32 PFI 5/P0.5 (port0/line5)
33 D GND
34 PFI 6/P0.6 (port0/line6)
35 PFI 7/P0.7 (port0/line7)
36 D GND
Table 4. USB-6421 AO/DIO Connector Signal Descriptions
Signal Function Reference Direction Description
AO <0..1> Analog output channels AO GND Output Supplies the voltage output of the AO channels.
AO GND Analog output ground AO GND is the reference for the AO channels.

AI GND, AO GND, D GND, and CHSGND are all connected internally.

+5 V +5 V power source D GND Output Provides current limited +5 V power output that can be used to power external circuitry. Refer to the +5 V Power Source section for more information. Leave this pin open if you do not use it.
PFI <0..15>/P0.<0..15> Port 0 digital I/O channels D GND Input or output

Digital channels that can be individually configured as input or output.

These channels are referred to as port0/line0:15 in software when used as digital I/O. They are referred to as PFI 0:15 when used for other purposes, like timing I/O.

Can also be individually configured for the following uses.

  • Digital I/O
  • Counter/timer input
  • Counter/timer output
  • External timing or trigger signal input for AI, AO, DI, DO, counter, or timers
  • Timing or trigger signal output from AI, AO, DI, DO, counter, or timers
D GND Digital ground Supplies the reference for the P0.<0..15> pins and +5 V pin.

AI GND, AO GND, D GND, and CHSGND are all connected internally.

CHSGND Chassis ground Connects directly to the chassis ground of the USB-6421 enclosure. It can be used as a termination point for shielded cables to help improve measurement quality.
ID 1 This feature is not supported yet.

USB-6421 (OEM) AI Connector Pinout

Use the pinout to connect to analog input terminals on the USB-6421 (OEM).

Figure 3. USB-6421 (OEM) AI Connector Pinout


Table 5. USB-6421 (OEM) AI Connector Pin Assignments
Pin Signal
1 AI 8
2 AI 0
3 AI 9
4 AI 1
5 AI GND
6 AI GND
7 AI 10
8 AI 2
9 AI 11
10 AI 3
11 AI GND
12 AI GND
13 AI 12
14 AI 4
15 AI 13
16 AI 5
17 AI GND
18 AI GND
19 AI 14
20 AI 6
21 AI 15
22 AI 7
23 AI GND
24 NR (AI SENSE)
25 AI GND
26 NR (AI SENSE)
27 No connect
28 No connect
29 No connect
30 No connect
31 AI GND
32 AI GND
33 No connect
34 No connect
35 No connect
36 No connect
37 AI GND
38 AI GND
39 No connect
40 No connect
41 No connect
42 No connect
43 AI GND
44 AI GND
45 No connect
46 No connect
47 No connect
48 No connect
49 CHSGND
50 ID 0
Table 6. USB-6421 (OEM) AI Connector Signal Descriptions
Signal Function Reference Direction Description
AI <0..7> Analog input channels Varies Input

Supports differential or single-ended measurement modes. The default configuration is differential mode.

In differential mode, these channels are the positive input for the differential pair. The negative input of the differential pair is located directly beneath the positive input.

In single-ended mode, each signal is a separate analog input voltage channel. The ground reference in single-ended mode is configurable. In referenced single-ended (RSE) mode, AI GND is the reference for the voltage measurement. In non-referenced single-ended (NRSE) mode, the NR pin is the reference.

Note You can configure the input mode per channel.
AI <8..15> Analog input channels Varies Input

Supports single-ended measurements only. The default configuration is RSE mode. In RSE mode, AI GND is the reference for the voltage measurement. In NRSE mode, the NR pin is the reference.

For differential measurements, refer to the descriptions for AI <0..7>.

AI GND Analog input ground The reference point for single-ended measurements in RSE mode and the bias current return point for differential measurements.

AI GND, AO GND, D GND, and CHSGND are all connected internally.

NR (AI SENSE) AI SENSE for NRSE mode Input The AI SENSE pin is labeled "NR" because it is used when the input terminal is configured to NRSE mode. In NRSE mode, AI SENSE acts as a remote sense of a reference voltage that can be at a different voltage potential than AI GND.
CHSGND Chassis ground Connects directly to the chassis ground lug of the USB-6421 (OEM). It can be used as a termination point for shielded cables to help improve measurement quality.
ID 0 This feature is not supported yet.

USB-6421 (OEM) AO/DIO Connector Pinout

Use the pinout to connect to analog output and digital input/output terminals on the USB-6421 (OEM).

Figure 4. USB-6421 (OEM) AO/DIO Connector Pinout


Table 7. USB-6421 (OEM) AO/DIO Connector Pin Assignments
Pin Signal
1 CHSGND
2 ID 1
3 AO GND
4 AO 0
5 AO GND
6 AO 1
7 AO GND
8 No connect
9 AO GND
10 No connect
11 D GND
12 +5 V
13 PFI 8/P0.8 (port0/line8)
14 PFI 0/P0.0 (port0/line0)
15 D GND
16 D GND
17 PFI 9/P0.9 (port0/line9)
18 PFI 1/P0.1 (port0/line1)
19 D GND
20 D GND
21 PFI 10/P0.10 (port0/line10)
22 PFI 2/P0.2 (port0/line2)
23 D GND
24 D GND
25 PFI 11/P0.11 (port0/line11)
26 PFI 3/P0.3 (port0/line3)
27 D GND
28 D GND
29 PFI 12/P0.12 (port0/line12)
30 PFI 4/P0.4 (port0/line4)
31 D GND
32 D GND
33 PFI 13/P0.13 (port0/line13)
34 PFI 5/P0.5 (port0/line5)
35 D GND
36 D GND
37 PFI 14/P0.14 (port0/line14)
38 PFI 6/P0.6 (port0/line6)
39 D GND
40 D GND
41 PFI 15/P0.15 (port0/line15)
42 PFI 7/P0.7 (port0/line7)
43 PWR_GR
44 PWR_RED
45 USER_GR
46 USER_RED
47 No connect
48 No connect
49 No connect
50 No connect
Table 8. USB-6421 (OEM) AO/DIO Connector Signal Descriptions
Signal Function Reference Direction Description
AO <0..1> Analog output channels AO GND Output Supplies the voltage output of the AO channels.
AO GND Analog output ground AO GND is the reference for the AO channels.

AI GND, AO GND, D GND, and CHSGND are all connected internally.

+5 V +5 V power source D GND Output Provides current limited +5 V power output that can be used to power external circuitry. Refer to the +5 V Power Source section for more information. Leave this pin open if you do not use it.
PFI <0..15>/P0.<0..15> Port 0 digital I/O channels D GND Input or output

Digital channels that can be individually configured as input or output.

These channels are referred to as port0/line0:15 in software when used as digital I/O. They are referred to as PFI 0:15 when used for other purposes, like timing I/O.

Can also be individually configured for the following uses.

  • Digital I/O
  • Counter/timer input
  • Counter/timer output
  • External timing or trigger signal input for AI, AO, DI, DO, counter, or timers
  • Timing or trigger signal output from AI, AO, DI, DO, counter, or timers
D GND Digital ground Supplies the reference for the P0.<0..15> pins and +5 V pin.

AI GND, AO GND, D GND, and CHSGND are all connected internally.

CHSGND Chassis ground Connects directly to the chassis ground lug of the USB-6421 (OEM). It can be used as a termination point for shielded cables to help improve measurement quality.
PWR_GR USB PWR LED green color DGND Output

Digital logic control signal that is high when the USB PWR LED is green or yellow. You can use this signal to drive an external LED.

Leave this pin open if you do not use it.

PWR_RED USB PWR LED red color DGND Output

Digital logic control signal that is high when the USB PWR LED is red or yellow. You can use this signal to drive an external LED.

Leave this pin open if you do not use it.

USER_GR User LED green color DGND Output

Digital logic control signal that is high when the USER LED is green or yellow. You can use this signal to drive an external LED.

Leave this pin open if you do not use it.

USER_RED User LED red color DGND Output

Digital logic control signal that is high when the USER LED is red or yellow. You can use this signal to drive an external LED.

Leave this pin open if you do not use it.

ID 1 This feature is not supported yet.

Analog Input

Number of channels

16 single-ended or 8 differential

ADC resolution

16 bits

DNL

No missing codes guaranteed

INL

Refer to AI Absolute Accuracy

Sample rate

Single channel maximum

250 kS/s

Multichannel maximum (aggregate)

250 kS/s

Minimum

No minimum

Timing resolution

10 ns

Timing accuracy

50 ppm of sample rate

Input coupling

DC

Input range

±0.2 V

±1 V

±5 V

±10 V

Power on state

Differential Mode at 10 V Range

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

All input ranges (±0.2V, ±1 V, ±5 V, ±10 V)

±11 V to AI GND

Table 9. Input Impedance
Device on AI+ to AI GND >10 GΩ in parallel with 50 pF
AI- to AI GND >10 GΩ in parallel with 50 pF
Device off AI+ to AI GND 1,250 Ω
AI- to AI GND 1,250 Ω

Input bias current

±30 pA typical

±1 nA maximum over full temperature range

Crosstalk (at 100 kHz)

Differential channels

-65 dB

Single-ended channels

-50 dB

Small signal bandwidth (-3 dB)

Input range ±10 V

630 kHz

Input range ±5 V

510 kHz

Input range ±1 V, ±0.2 V

490 kHz

Figure 5. USB-6421 Small Signal Bandwidth versus Frequency


Common-mode rejection ratio (CMRR) (DC to 60 Hz)

Differential mode

100 dB

Non-referenced single-ended (NRSE) mode

90 dB

Figure 6. USB-6421 CMRR versus Frequency


Input FIFO size

8,191 samples shared among channels used

Scan list memory

4,095 entries

Data transfers

USB Signal Stream, programmed I/O

Overvoltage protection for AI<0..15> and NR (AI Sense) pins

Device on

±30 V for up to two AI pins

Device off

±20 V for up to two AI pins

Input current during overvoltage condition

±16 mA maximum per AI pin

±16 mA maximum per NR pin

Table 10. Settling Time for Multi-channel Measurements at Full-Scale Step
Input Range ±90 ppm (6 LSB) ±30 ppm (2 LSB) ±15 ppm (1 LSB)
±0.2 V, ±1 V, ±5 V, ±10 V 4 µs 6 µs 7 µs
Note Refer to the Multi-channel Scanning Considerations section in the USB-6421 and USB-6421 (OEM) User Manual for the best settling time performance.
Figure 7. USB-6421 Settling Error versus Time for Different Source Impedances


Analog Triggers

Source

AI<0..15>

Purpose

Reference trigger only

Level

Full scale (depending on AI input range for the selected trigger channel)

Resolution

16-bit

Accuracy

Same as AI Absolute Accuracy

Modes

Rising-edge, rising-edge with hysteresis, falling-edge, falling-edge with hysteresis, entering window, leaving window

AI Absolute Accuracy (Warranted)

Notice The input channels of the USB-6421 are sensitive to electromagnetic interference (EMI). As a result, you might experience reduced measurement accuracy or temporary performance degradation with cables routed through strong EMI environments. To ensure optimal performance, either avoid such environments, or carefully select and route cables or probes connected to the USB-6421. This notice does not apply to the USB-6421 (OEM).
Table 11. AI Absolute Accuracy
Nominal Range, Positive Full Scale (V) Nominal Range, Negative Full Scale (V) 2 Years Residual Gain Error (ppm of Reading) 10 Years Residual Gain Error (ppm of Reading) Gain Tempco (ppm of Range/°C) Residual Offset Error (ppm of Range) Offset Tempco (ppm of Range/°C) Random Noise, σ (μV RMS) 2 Years Absolute Accuracy at Full Scale (μV) 10 Years Absolute Accuracy at Full Scale (μV)
10 -10 102 172 15 21 40 240 2,607 3,307
5 -5 110 180 15 23 40 122 1,354 1,704
1 -1 110 180 15 26 44 28 278 348
0.2 -0.2 122 192 15 78 60 13 72 86
Note Absolute accuracy at full scale on the analog input channels is determined using the following assumptions:
  • Temp Change From Last External Cal = 10 °C
  • Temp Change From Last Internal Cal = 1 °C
  • Number of readings = 10,000
  • Coverage Factor = 3σ
Note Accuracies listed are valid for up to 2 and 10 years from the device external calibration.

Reference Tempco

5 ppm/°C

INL error

32 ppm of range

AI Absolute Accuracy Equation

Absolute Accuracy = Reading * Gain Error + Range * Offset Error + Noise Uncertainty
  • Gain Error = Residual Gain Error + Gain Tempco * Temp Change From Last Internal Cal + Reference Tempco * Temp Change From Last External Cal
  • Offset Error = Residual Offset Error + Offset Tempco * Temp Change From Last Internal Cal + INLError 
  • Noise Uncertainty = Random Noise * 310,000

For a coverage factor of 3 σ and averaging 10,000 points.

AI Absolute Accuracy Example

For example, on the 10 V range for 2 years calibration interval, the absolute accuracy at full scale is as follows:

  • Gain Error: 102 ppm + 15 ppm * 1 + 5 ppm * 10 = 167 ppm
  • Offset Error: 21 ppm + 40 ppm * 1 + 32 ppm = 93 ppm
  • Noise Uncertainty: 240 μV * 310,000 = 7.2 μV
  • Absolute Accuracy: 10 V * Gain Error +10 V * Offset Error + Noise Uncertainty = 2,607 μV

Analog Output

Number of channels

2

DAC resolution

16 bits

DNL

±1 LSB

Monotonicity

16 bits guaranteed

Maximum update rate (simultaneous)

All channels

250 kS/s

Timing accuracy

50 ppm of sample rate

Timing resolution

10 ns

Output range

±10 V

Output coupling

DC

Output impedance[1]1 Output impedance excludes cabling impedance.

0.05 Ω

Output current drive

±2 mA

Overdrive protection during power on/off

±30 V

Overdrive current

2.8 mA

Power-on state

Less than ±5 mV

Output FIFO size

16,383 samples shared among channels used

Data transfers

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)

25 µs with 50 pF load

Slew rate

8 V/µs

AO glitch

Device power up

±0.9 V peak for 8 ms

Device power down, reset, or USB hot unplug

-1.4 V peak for 400 ns

Glitch energy mid-scale code transition

±5 mV for 5 µs

Crosstalk (at 10 kHz)

< -100 dB

AO Absolute Accuracy (Warranted)

Notice The output channels of the USB-6421 are sensitive to electromagnetic interference (EMI). As a result, you might experience reduced measurement accuracy or temporary performance degradation with cables routed through strong EMI environments. To ensure optimal performance, either avoid such environments, or carefully select and route cables or probes connected to the USB-6421. This notice does not apply to the USB-6421 (OEM).

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.

Table 12. AO Absolute Accuracy
Nominal Range, Positive Full Scale (V) Nominal Range, Negative Full Scale (V) 2 Years Residual Gain Error (ppm of Reading) 10 Years Residual Gain Error (ppm of Reading) Gain Tempco (ppm of Range/°C) Residual Offset Error (ppm of Range) Offset Tempco (ppm of Range/°C) 2 Years Absolute Accuracy at Full Scale (μV) 10 Years Absolute Accuracy at Full Scale (μV)
10 -10 106 176 17 34 40.7 2,787 3,487
Note Accuracies listed are valid for up to 2 and 10 years from the device external calibration.

Reference Tempco

5 ppm/°C

INL error

31 ppm of range

AO Absolute Accuracy Equation

Absolute Accuracy = Output Value * Gain Error + Range * Offset Error
  • Gain Error = Residual Gain Error + Gain Tempco * Temp Change From Last Internal Cal + Reference Tempco * Temp Change From Last External Cal
  • Offset Error = Residual Offset Error + Offset Tempco * Temp Change From Last Internal Cal + INLError 

Digital I/O (PFI)

Number of channels

16

Capabilities

Static Digital I/O, Waveform Digital I/O, PFI, Counter, Timer, or Trigger I/O (configurable per line)

Direction control

Each terminal can be programmed individually as input or output

Logic family

Selectable in software. All lines share the same setting.

5 V (LVCMOS)

3.3 V

2.5 V

1.8 V

Default logic family setting

5.5 V (LVCMOS)

Electrical Characteristics

Ground reference

D GND

Direction control

Program each as input or output individually

Pull-down resistor

47 kΩ

Input voltage protection

±20 V per line, up to two lines simultaneously

Notice Stresses beyond those listed under the Input voltage protection specification may cause permanent damage to the USB-6421.

Static Digital I/O Capabilities

Channel names in software

Port0/line0:15

Waveform Digital I/O Capabilities

Channel names in software

Port0/line0:15

Port/sample size

Up to 16 bits

Waveform generation (DO) FIFO

8,191 samples

Waveform acquisition (DI) FIFO

1,023 samples

DO or DI sample clock frequency

0 MHz to 10 MHz, system and bus activity dependent

Data transfers

USB Signal Stream, programmed I/O

Digital line filter settings

160 ns

10.24 µs

5.12 ms

Disable

PFI Functionality

Channel names in software

PFI0:15

Functionality

Timing input

Timing output

Timing output sources

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

Recommended Operating Conditions

Output high current (IOH)

DIO<0..15>

-10 mA maximum per channel

Output low current (IOL)

DIO<0..15>

10 mA maximum per channel

Note The maximum output current is shared between all channels and the +5 V power source.
Table 13. Digital Input Logic Levels
Logic Family Input Low Voltage (VIL) Input High Voltage (VIH)
Minimum Maximum Minimum Maximum
1.8 V -0.5 V 0.62 V 1.19 V 5.25 V
2.5 V -0.5 V 0.70 V 1.76 V 5.25 V
3.3 V -0.5 V 0.80 V 2.00 V 5.25 V
5.0 V -0.5 V 1.46 V 3.66 V 5.25 V
Table 14. Digital Output Logic Level
Logic Family Current Output Low Voltage (VOL) Maximum Output High Voltage (VOH) Minimum
1.8 V 4 mA 0.36 V 1.39 V
2.5 V 4 mA 0.32 V 2.16 V
3.3 V 4 mA 0.31 V 2.97 V
5.0 V 4 mA 0.30 V 4.59 V

Digital I/O Characteristics

IIL input low current (VIN = 0 V)

-1 µA maximum

IIH input low current (VIN = 5 V)

110 µA maximum

Figure 8. IOH versus VOH, 1.8 V Logic Family


Figure 9. IOL versus VOL, 1.8 V Logic Family


Figure 10. IOH versus VOH, 2.5 V Logic Family


Figure 11. IOL versus VOL, 2.5 V Logic Family


Figure 12. IOH versus VOH, 3.3 V Logic Family


Figure 13. IOL versus VOL, 3.3 V Logic Family


Figure 14. IOH versus VOH, 5.0 V Logic Family


Figure 15. IOL versus VOL, 5.0 V Logic Family


General-Purpose Counters

Number of counters/timers

4

Resolution

32 bits

Counter measurements

Edge counting

Pulse

Pulse width

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

Frequency division

Equivalent time sampling

Internal base clocks

100 MHz

20 MHz

100 kHz

External base clock frequency

0 MHz to 25 MHz

Base clock accuracy

50 ppm

Inputs

Gate

Source

HW_Arm

Aux

A

B

Z

Up_Down

Sample Clock

Routing options for inputs

Any PFI, many internal signals

FIFO

1,023 samples per counter

Data transfers

USB Signal Stream, Programmed I/O

Frequency Generator

Number of channels

1

Base clocks

100 MHz

20 MHz

100 kHz

Divisors

1 to 16

Base clock accuracy

50 ppm

Output can be available on any PFI terminal.

External Digital Triggers

Source

Any PFI

Polarity

Software-selectable for most signals

Analog input function

Start Trigger

Reference Trigger

Pause Trigger

Sample Clock

Sample Clock Timebase

Analog output function

Start Trigger

Pause Trigger

Sample Clock

Sample Clock Timebase

Counter/timer functions

Gate

Source

HW_Arm

Aux

A

B

Z

Up_Down

Sample Clock

Digital waveform generation (DO) function

Start Trigger

Pause Trigger

Sample Clock

Sample Clock Timebase

Digital waveform acquisition (DI) function

Start Trigger

Reference Trigger

Pause Trigger

Sample Clock

Sample Clock Timebase

Bus Interface

USB compatibility

USB 3.0/USB 3.1 Gen 1/USB 3.2 Gen 1 SuperSpeed or USB 2.0 Hi-Speed[2]2 Operating on a Hi-Speed bus results in lower performance, and you might not be able to achieve maximum sampling/update rates.

USB Signal Stream

8, can be used for analog input, analog output, digital input, digital output, or counter input

USB connector

USB Type-C

USB-6421 (OEM) LED Color Control Status

Logic level 3.3 V
Output resistance 470 Ω
Protection ±20 V

+5 V Power Source

Voltage accuracy No load +4.87 V to +5.22 V
Maximum current +4.76 V to 5.17 V
Maximum load current[3]3 The USB-6421 will self-detect the power capability of USB host to configure the current limit. If the USB-6421 is at 280 mA limit, it will lower the current limit to 50 mA if there is overdrive or fault condition. The current limit will be reset back to the default 280 mA limit when the fault or load is removed.

Connected to USB 2.0 Hi-Speed port with 2.5 W power

50 mA

Connected to USB 3.0 SuperSpeed port with ≥4.5 W power

280 mA

Power on state

Always on (no user control)

Overdrive protection during power on/off

±30 V

Power Requirements

Caution The protection provided by the USB-6421 can be impaired if it is used in a manner not described in the USB-6421 and USB-6421 (OEM) User Manual.

USB power rating

3.8 W (760 mA at nominal 5 V)

Power input mating connector

USB Type-C plug for power and data

Current Limit

DIO and +5 V terminals combined[4]4 The USB-6421 will self-detect the power capability of the USB host to configure the current limit. If the USB-6421 is at 280 mA limit, it will lower the current limit to 50 mA if there is an overdrive or fault condition. The current limit will be reset back to the default 280 mA limit when the fault or load is removed. Connected to USB 2.0 Hi-Speed port with 2.5 W power 50 mA
Connected to USB 3.0 SuperSpeed port with ≥4.5 W power 280 mA

Maximum Working Voltage

Maximum working voltage refers to the signal voltage plus the common-mode voltage.

Channel to earth

11 V, Measurement Category I

Measurement Category

This product is rated for Measurement Category I.

Caution Do not connect the product to signals or use for measurements within Measurement Categories II, III, or IV.
Remarque Ne pas connecter le produit à des signaux dans les catégories de mesure II, III ou IV et ne pas l'utiliser pour effectuer des mesures dans ces catégories.

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.

Note Measurement Categories CAT I and CAT O are equivalent. These test and measurement circuits are for other circuits not intended for direct connection to the MAINS building installations of Measurement Categories CAT II, CAT III, or CAT IV.

Physical Characteristics

Product Version I/O Connector
USB-6421 2x 36-position spring terminals
USB-6421 (OEM) 2x 50-pin, 0.100 in. x 0.100 in. ribbon cable header
Product Version Dimensions
USB-6421 116.7 mm x 177.0 mm x 30.4 mm (4.59 in. x 6.97 in. x 1.20 in.)
USB-6421 (OEM) 109.22 mm x 167 mm x 13.6 mm (4.3 in. x 6.58 in. x 0.14 in.)
Product Version Weight
USB-6421 590 g (1.30 lb)
USB-6421 (OEM) 95.1 g (0.21 lb)

Field Wiring Specifications

The following field wiring specifications do not apply to the USB-6421 (OEM).

Use copper wiring for all connections unless otherwise stated.

Gauge

0.14 mm2 to 1.5 mm2 (26 AWG to 16 AWG) copper conductor wire

Wire strip length

10 mm (0.394 in.) of insulation stripped from the end

Temperature rating

-25 °C to 120 °C

Wires per terminal

One wire per spring terminal; two wires per spring terminal using a 2-wire ferrule

Ferrules

Single ferrule, uninsulated

0.14 mm2 to 1.5 mm2 (26 AWG to 16 AWG)

10 mm barrel length

Single ferrule, insulated

0.14 mm2 to 1.0 mm2 (26 AWG to 18 AWG)

12 mm barrel length

Two-wire ferrule, insulated

2x 0.34 mm2 (22 AWG)

12 mm barrel length

Connector securement

Securement type

Screw flanges

Torque for screw flanges

0.2 N · m (1.80 lb · in.)

USB-6421 (OEM) Connectors

You can connect the following I/O connectors on the USB-6421 (OEM) using a 0.100 in. x 0.100 in. pitch ribbon cable or PCB socket. Refer to the manufacturer's data sheet for compatibility information.

Table 15. USB-6421 (OEM) Connectors
Connector Component Reference Designator(s) on PCB Manufacturer Manufacturer Part Number
AI 50-pin header P1 3M N2550-6002RB
AO/DIO 50-pin header P2 3M N2550-6002RB

Environmental Characteristics

Temperature

Operating temperature

0 °C to 55 °C

Storage temperature

-20 °C to 70 °C

Humidity

Operating humidity[5]5 The USB-6421 will perform at the full accuracy specification up to 90% RH operating humidity at ≤40 °C.

10% RH to 90% RH, noncondensing

Storage humidity

5% RH to 95% RH, noncondensing

Pollution Degree

2

Maximum altitude

2,000 m

The following shock and vibration specifications do not apply to the USB-6421 (OEM).

Shock and vibration

Operating vibration

5 Hz to 500 Hz, 0.3 g RMS

Non-operating vibration

5 Hz to 500 Hz, 2.4 g RMS

Operating shock

30 g, half-sine, 11 ms pulse

Calibration

Recommended warm-up time

15 minutes

Recommended calibration interval

2 years

1 Output impedance excludes cabling impedance.

2 Operating on a Hi-Speed bus results in lower performance, and you might not be able to achieve maximum sampling/update rates.

3 The USB-6421 will self-detect the power capability of USB host to configure the current limit. If the USB-6421 is at 280 mA limit, it will lower the current limit to 50 mA if there is overdrive or fault condition. The current limit will be reset back to the default 280 mA limit when the fault or load is removed.

4 The USB-6421 will self-detect the power capability of the USB host to configure the current limit. If the USB-6421 is at 280 mA limit, it will lower the current limit to 50 mA if there is an overdrive or fault condition. The current limit will be reset back to the default 280 mA limit when the fault or load is removed.

5 The USB-6421 will perform at the full accuracy specification up to 90% RH operating humidity at ≤40 °C.