One of the most important steps in project development is determining which device provides the best solution for your application. Current test and measurement systems usually require some form of digital input and output, whether for toggling a few digital control lines to change a device's state or for generating advanced patterns to validate a custom circuit. National Instruments offers a wide range of digital products to help meet the digital needs of your applications.
The four main digital products available from National Instruments include:
- Industrial digital I/O
- Reconfigurable I/O
- M Series multifunction DAQ
- Digital waveform generator/analyzers (high-speed digital I/O)
Digital I/O Product Feature Comparisons
The following table highlights the strengths of the features available on the four main National Instruments digital products. You can find more information on the different product lines at the corresponding links in the table.
| Features |
Industrial
Digital I/O |
Reconfigurable
I/O |
M Series |
High-Speed
Digital I/O |
|---|
| Fast Clock and Data Rates |
 |
 |
|
 |
| Flexible Voltage Levels |
|
|
|
|
| Onboard Memory |
|
|
|
|
| High-Voltage Levels |
|
|
|
|
| Multidevice Synchronization |
|
|
|
|
| Channel-to-Channel Isolation |
|
|
|
|
| Hardware-Timed Digital I/O |
|
|
|
|
| Dedicated Digital Timing Engine |
|
|
|
|
| Portable Solution |
|
|
|
|
| Phase-Shifting Data (Data Delay) |
|
|
|
|
| Input Filters for Noise and Chatter |
|
|
|
|
| Cost |
|
|
|
|
- Good
- Better
- Best
For specific technical information on high-speed waveform generator/analyzers and industrial I/O devices, review these online documents:
Digital I/O Specification Comparisons
The following table provides a quick specifications comparison of the different National Instruments digital devices. For more information on a specific device, refer to the product pages.
| Model Name |
Max Data Rate (Mb/s) |
Max Pins Per Board |
Voltage Levels |
Max Current |
Multidevice Delay |
Max Onboard Memory |
Isolation |
Platform |
|---|
| High-Speed Digital I/O |
| NI 656x |
400 Mb/s |
16 |
LVDS |
LVDS- compliant |
T-Clock (10s of ps) |
128 Mb/ch |
- |
PXI |
| NI 655x |
100 Mb/s |
20 |
Programmable -2.0 to 5.5 V |
50 mA |
T-Clock (10s of ps) |
64 Mb/ch |
- |
PXI, PCI |
| NI 654x |
100 Mb/s |
32 |
Software-selectable 5.0, 3.3, 2.5, 1.8 V |
32 mA |
T-Clock (10s of ps) |
64 Mb/ch |
- |
PXI, PCI |
| NI 6534 |
20 Mb/s |
32 |
5 V TTL/CMOS |
24 mA |
RTSI (±1 sample) |
32 Mb/ch1 |
- |
PXI, PCI, PCMCIA, ISA |
| NI 6533 |
20 Mb/s |
32 |
5 V TTL/CMOS |
24 mA |
RTSI (±1 sample) |
- |
- |
PXI, PCI, PCMCIA, ISA |
| Industrial Digital I/O |
| NI 652x |
Software-timed |
24 input, 24 output |
±60 VDC |
150 mA |
RTSI (±1 sample) |
- |
Channel-channel |
PXI, PCI |
| NI 651x |
Software-timed |
32 or 64 |
±30 VDC |
500 mA |
- |
- |
Bank |
PXI, PCI |
| NI 650x |
Software-timed |
24 or 96 |
5 V TTL/CMOS |
24 mA |
- |
- |
- |
PXI, PCI, PCMCIA, USB |
| Multifunction DAQ (M Series and S Series) |
| NI 625x or NI 628x |
10 Mb/s |
32 |
5 V TTL/CMOS |
24 mA |
RTSI (±1 sample) |
- |
- |
PXI, PCI |
| NI 622x |
1 Mb/s |
32 |
5 V TTL/CMOS |
24 mA |
RTSI (±1 sample) |
- |
- |
PXI, PCI |
| NI 61xx |
10 Mb/s |
8 |
5 V TTL/CMOS |
24 mA |
RTSI (±1 sample) |
- |
- |
PXI, PCI |
| Reconfigurable I/O (R Series and CompactRIO) |
| cRIO-9411 |
2 Mb/s |
6 (input) |
Differential or 5 V TTL |
- |
- |
- |
Channel-earth |
CompactRIO |
| cRIO-947x |
1 Mb/s |
8 (output) |
5 to 30 V |
1 A |
- |
- |
Channel-earth |
CompactRIO |
| cRIO-942x |
"0.1 to 1
Mb/s" |
8 or 32 (input) |
24 V |
- |
- |
- |
Channel-earth |
CompactRIO |
1 The 32 Mbit/channel applies to 8 bit groups
