The NI 660x and NI 661x counter/timers use the National Instruments NI-TIO, a National Instruments ASIC designed specifically to meet the counting and timing requirements of measurement applications that are beyond the capabilities of off-the-shelf components. The wider functionality and simpler programming interface make these devices ideal for counting and timing applications.
In addition to counter/timer functionality, the NI 660x and NI 661x devices include TTL-compatible digital I/O ports that are bit-configurable for input or output. These devices are suited for frequency measurement, generation of retriggerable pulses, frequency shift-keying, two-signal edge separation measurements, continuous buffered event counting, and continuous buffered pulse train measurements. The NI 660x and NI 661x counter/timer devices are readily integrated into measurement systems that require synchronization across multiple hardware devices because they are equipped with the National Instruments PXI Trigger bus or the RTSI bus.
In addition to the 660x and 661x boards, NI 6624 devices are industrial isolated timing interfaces for PCI bus computer systems. You can use the eight 32-bit channel-channel optically isolated counter/timers of the NI 6624 devices to perform a wide variety of buffered measurements or other counter/timer tasks, including position or quadrature encoder measurement, edge counting, period measurement, pulse-width measurement, frequency measurement, semi-period measurement, two-edge separation measurement, PWM generation, pulse, and pulse-train generation.
| Platforms | PCI | PXI | PCI, PXI | PCI | PXI Express | PXI Express |
| Counter ASIC | NI-TIO | NI-TIO | NI-TIO | NI-TIO | NI-TIO | NI-TIO |
| Counter Channels | 8 | 8 | 8 | 4 | 8 | 8 |
| Counter Resolution | 32 | 32 bits | 32 bits | 32 bits | 32 bits | 32 bits |
| Isolation | Ch-Ch Optically Isolated | None | None | None | None | None |
| Standard Timebases | 20 MHz | 80 MHz, | 80 MHz, | 20 MHz, | 100 MHz, | 100 MHz |
| 100 kHz | 20 MHz, | 20 MHz, | 100 kHz | 20 MHz | 20 MHz | |
| 100 kHz | 100 kHz | 100 kHz | 100 kHz | |||
| Timebase Stability | 50 ppm | 75 ppb | 50 ppm | 50 ppm | 50 ppm | 75 ppb |
| Prescalers | none | X8, X2 | X8, X2 | X8, X2 | none | none |
| Max Frequency (Without prescalers) | 20 MHz | 80 MHz | 80 MHz | 20 MHz | 100 MHz | 100 MHz |
| Max Frequency (With prescalers) | N/A | 125 MHz | 125 MHz | 60 MHz | N/A | N/A |
| Digital I/O | 0 | up to 32 bits | up to 32 bits | up to 32 bits | up to 32 bits | up to 32 bits |
| DMA (on board) | 3 channels | 3 channels | 3 channels | 1 channel | 8 channels | 8 channels |
| RTSI Bus (synchronize multi-board operation) | Yes | Yes | Yes | Yes | Yes | Yes |
| Updown counter (external control for counting direction) | Yes | Yes | Yes | Yes | Yes | Yes |
| Quadrature Motion Encoder Support | Yes | Yes | Yes | Yes | Yes | Yes |
| Debounce Filters on I/O Lines | No | Yes | Yes | Yes | Yes | Yes |
| Two-Signal Edge-Separation Measurement | Yes | Yes | Yes | Yes | Yes | Yes |
| Hardware Start Trigger | Yes | Yes | Yes | Yes | Yes | Yes |
| Start Counters Simultaneously | Yes | Yes | Yes | Yes | Yes | Yes |
| Continuous Buffered Input | Yes | Yes | Yes | Yes | Yes | Yes |
| Dynamic Pulse Train Frequency Change | Yes | Yes | Yes | Yes | Yes | Yes |