II. Model Interpretation

PXI: 3U single-slot PXI module, compatible with PXI/PXIe mixed slots, standard PXI trigger bus.

6608: 660x (Timing/Counting + DIO); 8 = 8 channels, OCXO high-precision 10 MHz timing base, GPS synchronization, dual real-time clocks (6602 has no OCXO).

Core Identifier: 8×32-bit counter, 80 MHz, OCXO (75 ppb), GPS/PPS/IRIG-B, 32 channels DIO, 3 channels DMA, dual RTC.

III. Technical Parameters (25℃, after 5 minutes preheating)

Counter / Timer

Channels: 8 independent 32-bit add/subtract counters, maximum count value 2³² - 1.

Timing Base: OCXO 10 MHz (75 ppb stability, 0.075 ppm); optional 20 MHz / external input (up to 100 MHz).

Count Rate: 80 MHz (standard); pre-divided ×2/×8 up to 125 MHz.

Measurement: Event counting, period/frequency, pulse width (resolution 12.5 ns), duty cycle, quadrature encoder (4 times frequency).

Output: single pulse, pulse train, PWM (up to 40 MHz), retriggerable pulse.

Accuracy: OCXO temperature drift 75 ppb; long-term stability 20 ppb/year; dual RTC, GPS synchronization accuracy 300 ns.

Digital I/O

Channels: 32 5V TTL/CMOS bidirectional DIO; 8 dedicated, 24 channels shared with counters.

Level: input -0.3~5.5 V, output 0~5 V; single channel drive ±4 mA.

Filtering: per-channel programmable digital debounce / anti-windup (100 ns~100 ms).

Transmission: static I/O, handshake; maximum 20 MHz throughput.

Physical and Environmental

Size: 3U single-slot (160×100 mm).

Power Consumption: +5V@1.0~2.5 A, typical 12.5 W (OCXO preheating power consumption is high).

Connector: 68-pin SCSI-II shielded male connector, with latch.

Temperature: 0~55℃ (commercial); extended grade -40~+85℃.

Synchronization: PXI trigger bus, STAR trigger, external PFI, GPS/PPS/IRIG-B.

IV. Interface and Communication Configuration

Hardware Interface

I/O: 68-pin SCSI-II, including 8 groups of counters (SOURCE/GATE/UPDN/OUT) + 32 channels DIO + power / ground.

Clock / Trigger: OCXO 10 MHz output to PXI backplane; supports GPS PPS, IRIG-B, external 100 MHz clock.

Bus: PXI, 3 independent DMA channels, high-speed data transmission, low CPU usage.

Software and Drivers

Driver: NI-TIO, companion Counter/Timer Panel, Digital Waveform Editor.

Development Environment: LabVIEW, Python, C/C++, TestStand; supports GPS synchronization, encoder decoding, PWM generation, timing calibration.

Synchronization: Seamless synchronization with PXIe digitizers, AWGs, switches, power supplies, for high-precision mixed-signal ATE.

V. Core Functions OCXO Ultra Stable Time Base (75 ppb): 10 MHz constant temperature crystal oscillator, temperature drift 0.075 ppm, annual stability 20 ppb; output to PXI backplane, the entire system synchronized to 75 ppb level, suitable for metrology calibration, long-term stability testing.

8-channel 32-bit High-Speed Counting/Timing: 8 independent counters, 80 MHz base frequency + 125 MHz pre-divider; precise measurement of period/frequency/pulse width (12.5 ns resolution); supports quadrupling of orthogonal encoders for capturing motor position/velocity.

Dual Real-Time Clocks + GPS Global Synchronization: Dual RTCs, GPS PPS synchronization accuracy 300 ns; supports IRIG-B time code, multi-box cross-regional time correlation, event alignment, suitable for distributed testing, aerospace telemetry.

32-channel 5V TTL/CMOS DIO + De-Emphasis: 32 bidirectional DIO, 8 dedicated + 24 multiplexed; programmable digital filtering to eliminate contact jitter/stripping, suitable for industrial switches/sensors.

3 channels DMA High-Speed Transmission + Synchronous Counting: 3 DMA channels, zero CPU intervention; supports synchronous counting mode (to prevent duplicate counting), suitable for high-speed event recording, PWM closed-loop control, multi-axis synchronization.

Six, Application Scenarios

Metrology Calibration and Standard Source: Frequency/period value transmission, instrument calibration, time and frequency standards; OCXO as a reference clock, calibrating other instrument time bases.

Aerospace/Deterioration Testing: Satellite/rocket timing synchronization, event marking, telemetry data timestamp, high-precision pulse triggering; GPS synchronization to achieve cross-platform time unification.

Distributed Testing and Multi-Box Synchronization: N-second alignment of multiple sites/multi PXI chassis, event correlation, data fusion; time synchronization error < 1 μs for long-distance transmission.

High-Precision ATE and Semiconductor Testing: Chip timing verification, frequency/period testing, pulse generation, encoder interface testing; OCXO ensures long-term testing stability.

Research and Laboratory: Photon counting in physical experiments, particle detection, high-precision timing measurement, laser pulse triggering; long-term experimental time reference without drift.

Seven, Installation and Maintenance Instructions

Installation and Power On

Installation: Disconnect power, insert into 3U slot of PXI chassis (recommended Slot 2 STAR trigger slot), chassis reliably grounded, perform anti-static operation.

Power On: Preheat for 5 minutes (OCXO reaches stability), NI-TIO automatically self-checks; avoid frequent cold-hot restarts.

Environment: Keep air ducts unobstructed, 0~55℃; away from strong electromagnetic interference (motors, frequency converters).

Wiring and Operation

Wiring: 68-pin SCSI-II to avoid frequent plugging and unplugging, use dedicated shielded cables; ensure impedance matching for long-distance transmission.

Level Matching: Confirm DUT is 5V TTL/CMOS, prohibit mixing with LVDS/RS-422 to prevent module damage.

Clock Configuration: For high-precision synchronization, connect OCXO output to PXI backplane; connect GPS PPS to achieve global synchronization.

Daily Maintenance

Interface: Regularly clean 68-pin interface, prevent dust and moisture; install dust cover when not in use.

Software: Update NI-TIO driver and firmware to obtain function optimization and bug fixes.

Calibration: OCXO does not require regular calibration (factory calibration); annually check wiring tightness, cable integrity, and oxidation of connectors.