PCIe-6738 Specifications

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Updated2025-04-25
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PCIe-6738 Specifications

Definitions

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

Warranted Specifications describe the performance of a model under stated operating conditions and are covered by the model warranty. Specifications account for measurement uncertainties, temperature drift, and aging. Specifications are ensured by design or verified during production and calibration.

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—describes the performance met by a majority of models.

Typical-95—describes the performance met by 95% (≈2σ) of models with a 95% confidence.

Nominal—describes an attribute that is based on design, conformance testing, or supplemental testing.

Measured—describes the measured performance of a representative model.

Values are Typical unless otherwise noted.

Values are Warranted Specifications unless otherwise noted.

Conditions

Specifications are valid at 25 °C unless otherwise noted.

PCIe-6738 Pinout

Table 1. Default Counter/Timer Terminals
Counter/Timer Signal	Default PFI Terminal
CTR 0 SRC	PFI 5
CTR 0 GATE	PFI 6
CTR 0 AUX	PFI 4
CTR 0 OUT	PFI 7
CTR 0 A	PFI 5
CTR 0 Z	PFI 6
CTR 0 B	PFI 4
CTR 1 SRC	PFI 0
CTR 1 GATE	PFI 1
CTR 1 AUX	PFI 3
CTR 1 OUT	PFI 2
CTR 1 A	PFI 0
CTR 1 Z	PFI 1
CTR 1 B	PFI 3
CTR 2 SRC	PFI 5
CTR 2 GATE	PFI 6
CTR 2 AUX	PFI 4
CTR 2 OUT	PFI 7
CTR 2 A	PFI 5
CTR 2 Z	PFI 6
CTR 2 B	PFI 4
CTR 3 SRC	PFI 0
CTR 3 GATE	PFI 1
CTR 3 AUX	PFI 3
CTR 3 OUT	PFI 2
CTR 3 A	PFI 0
CTR 3 Z	PFI 1
CTR 3 B	PFI 3

Table 2. Signal Descriptions
Signal	Reference	Description
AO <0..31>	AO GND	Analog Output Channels—These terminals supply voltage output.
AO GND	—	Analog Output Ground—AO GND is the reference for the AO channels. When AO GND is listed next to an analog signal name, it is the dedicated ground reference for the listed signals (for example, AO GND 2/3 is the ground reference for AO 2 and AO 3). All ground references—AO GND and D GND—are connected on the device. Though AO GND and D GND are connected on the device, they are connected by small traces to reduce crosstalk between subsystems. Each ground may have a slight difference in potential.
D GND	—	Digital Ground—D GND supplies the reference for port 0, port 1 digital channels, PFI, and +5 V. When D GND is listed with a number, it is the dedicated ground reference for that PFI signal. All ground references—AO GND and D GND—are connected on the device. Though AO GND and D GND are connected on the device, they are connected by small traces to reduce crosstalk between subsystems. Each ground may have a slight difference in potential.
P0.<0,1>	D GND	Port 0 Digital I/O Channels—You can configure each signal individually as an input or output.
+5 V	D GND	+5 V Power Source—These terminals provide a fused +5 V power source.
PFI <0..7>/P1.<0..7>	D GND	Programmable Function Interface or Digital I/O Channels—Each of these terminals can be individually configured as a PFI terminal or a digital I/O terminal. As an input, each PFI terminal can be used to supply an external source for AO, DI, and DO timing signals or counter/timer inputs. As a PFI output, you can route many different internal AO, DI, or DO timing signals to each PFI terminal. You can also route the counter/timer outputs to each PFI terminal. As a port 1 digital I/O signal, you can individually configure each signal as an input or output.
NC	—	No connect—Do not connect signals to this terminal.

Analog Output

Number of channels

32 voltage outputs

Resolution

16 bits, 1 in 65,536

DNL

±1.0 LSB maximum

Unscaled data format^[1]¹ Used for writing unscaled or raw data and covers the range from negative full scale (0) to positive full scale (65,535).

Unsigned integer (0 to 65,535)

Monotonicity

16 bits

Accuracy

Refer to the AO Absolute Accuracy table

Maximum update rate (using local FIFO)^[2]² These numbers apply to continuous waveform generation using onboard memory only, which allows for the highest update rate by doing a single transfer of data over the bus. The maximum update rate in FIFO mode does not change regardless of the number of devices in the system.
1 channel	1 MS/s
8 channels (1 channel per bank) ³ All analog output channels are grouped into banks, as shown in your device pinout. Each bank consists of four AO channels using one DAC. Any channels being used within a single bank will update simultaneously. ^[3]	1 MS/s
32 channels ^[3]	350 kS/s

Timing accuracy (warranted)

50 ppm of sample rate

Timing resolution

10 ns

Output range

±10 V

Output coupling

Output impedance

0.2 Ω

Output current drive^[4]⁴ Analog output channels are designed for four-quadrant (source and sink) operation.

±10 mA

Overdrive protection

±15 V

Overdrive current

15 mA

Power-on state

±200 mV

Power-on/off glitch

3.0 V peak for 100 ms

FIFO buffer size

65,535 samples shared among channels used

Data transfers

DMA (scatter-gather), programmed I/O

AO waveform modes

Nonperiodic waveform
Periodic waveform regeneration mode from onboard FIFO
Periodic waveform regeneration from host buffer including dynamic update

Settling time, full scale step

15 µs to ±4 LSB

Slew rate

3.0 V/µs

Noise

1.0 mV RMS, DC to 1 MHz

AO update glitch
Magnitude	3.0 mV
Duration	10 µs
Glitch energy	3 nVs

Channel crosstalk

-65 dB with SHC68-68-A2 cable (generating a 10 V, 100 point sinusoidal at 100 kHz on the reference channel)

Output stability

Any passive load

Note AO update glitch is the glitch energy that occurs on all channels on the same bank as the result of a channel update, regardless of value. For example, if you update the value of AO 0, all channels within that bank AO <0..3> will experience this glitch regardless of whether their output voltages change.

Absolute Accuracy (Warranted)

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

Table 3. AO Absolute Accuracy
Nominal Range Positive Full Scale	Nominal Range Negative Full Scale	Residual Gain Error (ppm of Reading)	Gain Tempco (ppm/°C)	Reference Tempco (ppm/°C)	Offset Tempco (ppm)	Residual Offset Error (ppm of Range)	INL Error (ppm of Range)	Absolute Accuracy at Full Scale (µV)
10	-10	109	12	1	4	95	64	2,940

Note Accuracies listed are valid for up to two years from the device external calibration.

AO Absolute Accuracy Equation

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

GainError = ResidualGainError + GainTempco · (TempChangeFromLastInternalCal) + ReferenceTempco · (TempChangeFromLastExternalCal)
OffsetError = ResidualOffsetError + OffsetTempco · (TempChangeFromLastInternalCal) + INL_Error

Notice Electromagnetic interference can adversely affect the measurement accuracy of this product. The analog output pins of this device are not protected for lectromagnetic interference. As a result, this device may experience reduced accuracy or other temporary performance degradation when connected cables are routed in an environment with radiated or conducted radio frequency electromagnetic interference.

Digital I/O/PFI

Static Characteristics

Number of channels	10 total, 2 (P0.<0..1>), 8 (PFI<0..7>/P1.<0..7>)
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^[5]⁵ Stresses beyond those listed under Input voltage protection may cause permanent damage to the device.	±20 V on up to two pins

Waveform Characteristics (Port 0 Only)

Terminals used

Port 0 (P0.<0.1>)

Port/sample size

Up to 2 bits

Waveform generation (DO) FIFO

2,047 samples

Waveform acquisition (DI) FIFO

255 samples

DI Sample Clock Frequency

0 to 10 MHz, system and bus activity dependent

DO Sample Clock frequency
Regenerate from FIFO	0 to 10 MHz
Streaming from memory	0 to 10 MHz, system and bus activity dependent

Data transfers

DMA (scatter-gather), programmed I/O

Digital line filter settings

160 ns, 10.24 µs, 5.12 ms, disable

PFI/Port 1 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	90 ns, 5.12 µs, 2.56 ms, custom interval, disable; programmable high and low transitions; selectable per input

Recommended Operating Conditions

Input high voltage (V_IH)

2.2 V minimum, 5.25 V maximum

Input low voltage (V_IL)

0 V minimum, 0.8 V maximum

Output high current (I_OH)
P0.<0..1>	-24 mA maximum
PFI <0..7>/PI<0..7>	-16 mA maximum

Output low current (I_OL)
P0.<0..1>	24 mA maximum
PFI <0..7>/P1<0..7>	16 mA maximum

Electrical Characteristics


Level	Minimum	Maximum
Positive-going threshold (VT+) Negative-going threshold (VT-)	— 0.8 V	2.2 V —
Delta VT hysteresis (VT+ - VT-)	0.2 V	—
I_IL input low current (V_in = 0 V) I_IH input high current (V_in = 5 V)	— —	-10 µA 250 µA

Digital I/O Characteristics

Figure 2. PFI <0..7>/PI: I_OH versus V_OH

Figure 4. PFI <0..7>/P1: I_OL versus V_OL

Timing I/O

Number of counter/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 with dynamic updates, 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 (warranted)	50 ppm
Inputs	Gate, Source, HW_Arm, Aux, A, B, Z, Up_Down, Sample Clock
Routing options for inputs	Any PFI, RTSI, analog trigger, many internal signals
FIFO	127 samples per counter
Data transfers	Dedicated scatter-gather DMA controller for each counter/timer, programmed I/O

Phase-Locked Loop (PLL)

Number of PLLs

Table 4. Reference Clock Locking Frequencies
Reference Signal	Locking Input Frequency (MHz)
RTSI <0..7>	10, 20
PFI <0..7>	10, 20

Outside of PLL

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

External Digital Triggers

Source	Any PFI, RTSI
Polarity	Software-selectable for most signals
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

Device-to-Device Trigger Bus

Input source	RTSI <0..7>
Output destination	RTSI <0..7>
Output selections	10 MHz Clock; many internal signals
Debounce filter settings	90 ns, 5.12 µs, 2.56 ms, custom interval, disable; programmable high and low transitions; selectable per input

Bus Interface

Form factor	x4 PCI Express, specification v1.1 compliant
Slot compatibility	x4, x8, and x16 PCI Express slots^[6]⁶ Some motherboards reserve the x16 slot for graphics use. For PCI Express guidelines, visit ni.com/info and enter the Info Code PCIExpress.
DMA channels	7 DMA, analog output, digital input, digital output, counter/timer 0, counter/timer 1, counter/timer 2, counter/timer 3

Power Requirements

Notice The protection provided by the PCIe-6738 can be impaired if it is used in a manner not described in the user documentation.

+3.3 V	3.0 W
+12 V	14.0 W

Current Limits

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

+5 V terminal (connector 0)	1 A maximum ^[7]⁷ Has a self-resetting fuse that opens when current exceeds this specification.
P0/P1/PFI terminals combined	1.4 A maximum

Physical

Printed circuit board dimensions	16.8 cm × 11.1 cm (6.60 in. × 4.38 in.)
Weight	110 g (3.8 oz)
I/O connector	1 68-pin VHDCI
Form factor	Standard height, half length, single slot
Integrated air mover (fan)	No

Calibration

Recommended warm-up time	15 minutes
Calibration interval	2 years

Safety Voltages

Connect only voltages that are below these limits.

Channel-to-earth ground

±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 connect the PCIe-6738 to signals or use for measurements within Measurement Categories II, III, or IV.

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.

Environmental

Maximum altitude	2,000 m (800 mbar) (at 25 °C ambient temperature)
Pollution Degree	2

Indoor use only.

Note Clean the device with a soft, non-metallic brush. Make sure that the device is completely dry and free from contaminants before returning it to service.

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

Operating Environment

Operating temperature, local⁸ For PCI Express adapter cards with integrated air movers, NI defines the local operational ambient environment to be at the fan inlet. For cards without integrated air movers, NI defines the local operational ambient environment to be 25 mm (1 in.) upstream of the leading edge of the card. For more information about the local operational ambient environment definition for PCI Express adapter cards, visit ni.com/info and enter the Info Code pcielocalambient.^[8]

0 °C to 55 °C

(IEC 60068-2-1 and IEC 60068-2-2)

Operating humidity

10% to 90% RH, noncondensing

(IEC 60068-2-78)

System slot airflow

0.4 m/s (80 LFM)

Storage Environment

Ambient temperature range

-20 °C to 70 °C

(IEC 60068-2-1 and IEC 60068-2-2)

Relative humidity range

5% to 95% RH, noncondensing

(IEC 60068-2-78)

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.

Electromagnetic Compatibility 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
AS/NZS CISPR 11: Group 1, Class A emissions
FCC 47 CFR Part 15B: Class A emissions
ICES-001: Class A emissions

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 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.

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RoHS— NI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 Used for writing unscaled or raw data and covers the range from negative full scale (0) to positive full scale (65,535).

² These numbers apply to continuous waveform generation using onboard memory only, which allows for the highest update rate by doing a single transfer of data over the bus. The maximum update rate in FIFO mode does not change regardless of the number of devices in the system.

³ All analog output channels are grouped into banks, as shown in your device pinout. Each bank consists of four AO channels using one DAC. Any channels being used within a single bank will update simultaneously.

⁴ Analog output channels are designed for four-quadrant (source and sink) operation.

⁵ Stresses beyond those listed under Input voltage protection may cause permanent damage to the device.

⁶ Some motherboards reserve the x16 slot for graphics use. For PCI Express guidelines, visit ni.com/info and enter the Info Code PCIExpress.

⁷ Has a self-resetting fuse that opens when current exceeds this specification.

⁸ For PCI Express adapter cards with integrated air movers, NI defines the local operational ambient environment to be at the fan inlet. For cards without integrated air movers, NI defines the local operational ambient environment to be 25 mm (1 in.) upstream of the leading edge of the card. For more information about the local operational ambient environment definition for PCI Express adapter cards, visit ni.com/info and enter the Info Code pcielocalambient.

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