NI PCI-6514 Digital I/O Interface Card

Total Channels: 64 channels, including 32 sink/source current input channels and 32 source current output channels.

Voltage Range: Both digital input and output voltage ranges are ±30 VDC.

Current Drive: Single-channel digital I/O current drive is 75 mA, maintaining 75 mA when all channels operate simultaneously.

Isolation: Eight groups of isolated channels, electrically isolated from each other to prevent cross-channel interference and enhance system stability/reliability.

Programmable Power-Up State: Users can configure initial output states via software to ensure safe operation when connecting industrial actuators (e.g., pumps, valves, motors, relays).

Watchdog Function: Equipped with a digital I/O watchdog that switches to a configurable safe output state in case of computer/application failures, enabling secure system recovery.

Input Filtering: Programmable input filters remove noise, spikes, etc., from input signals, debounce digital switches/relays, and improve input stability/accuracy.

Dimensions: Approximately 140.72 mm × 113.54 mm (5.54 in × 4.47 in).

Interface: Features a 100-pin high-density SCSI connector for external device connection.

Power Requirements: Requires +3.3 VDC (300 mA) and +5 VDC (250 mA) power supplies.

Operating Temperature: 0°C to 55°C.

Storage Temperature: -20°C to 70°C.

Channel Configuration: 32 bidirectional digital I/O channels supporting TTL/CMOS levels (compatible with 0~5V signals), configurable as input, output, or tri-state modes.

Drive Capability: Maximum sink/source current of 40mA per channel, directly driving loads like relays, LEDs, or low-power solenoids.

Electrical Isolation: Partial channels (e.g., DI channels) support optical isolation (isolation voltage up to 2500 VRMS) for EMI resistance and device protection.

Signal Acquisition: External digital signals (e.g., switch quantities, encoder pulses) are connected to channels via interfaces, then level-converted to match internal logic levels.

Buffering & Filtering: Signals enter input buffer registers, with optional hardware filtering (e.g., debounce) to eliminate noise interference.

Data Reading: CPU or DMA controller reads register data via PCI bus, or triggers interrupts to notify system of data updates.

Data Writing: Software writes logic levels (0/1) to output registers via drivers.

Drive Amplification: Signals are amplified by drive circuits to meet external load requirements (e.g., driving relay coils).

Level Conversion: Outputs standard TTL/CMOS levels as configured, or converts to other levels (e.g., 24V industrial signals) via external circuits.

Built-in 2 × 32-bit counters/timers with maximum counting frequency up to 80MHz, supporting:

Trigger Types: Supports digital triggering (TTL level edge/level), software triggering, and external clock synchronization, enabling collaboration with other devices (e.g., oscilloscopes, motion controllers).

Interrupt Handling: Sends interrupt requests to CPU via PCI bus during trigger events for real-time response (e.g., fast capture of Sudden outbreak signals).

Bus Specifications: 32-bit/33MHz PCI bus with theoretical bandwidth of 132MB/s, supporting DMA (Direct Memory Access) mode.

DMA Transmission: Enables CPU-independent data transfer between memory and acquisition card buffers, suitable for high-speed batch data interaction (e.g., real-time monitoring of massive digital I/O states).

On-board FIFO (First-In-First-Out) buffers temporarily store I/O data to prevent loss during high-speed transmission.

Software can configure buffer size and overflow handling strategies (e.g., interrupt notification, data overwrite) via drivers.

Input channels integrate overvoltage protection circuits (e.g., TVS diodes) to prevent chip damage from external transient voltages (e.g., static electricity, surges).

Optically isolated channels block ground loop interference via optocouplers, suitable for strong electromagnetic industrial fields.

Supports NI standard signal conditioning platforms (e.g., SCB-68 terminal blocks) for external resistors, capacitors, etc., to implement signal voltage division, filtering, and other preprocessing.

Compatible with multi-card parallel expansion, achieving multi-device channel synchronous control via synchronization lines (e.g., distributed I/O systems).

Abstracts hardware operations via NI-DAQmx drivers, providing unified API interfaces to hide underlying register operation details.

Supports interrupt-driven and polling modes: Interrupt mode suits real-time response scenarios (e.g., external trigger events), while polling mode suits periodic data acquisition.

Initialization: Configures channel functions (I/O, isolation mode, etc.) via Measurement & Automation Explorer (MAX).

Programming Control: Calls driver functions using LabVIEW, Python, C++, etc., to implement data reading/writing, trigger setup, and timing control.

Real-time Monitoring: Driver layer provides status register query functions for diagnosing channel faults (e.g., overload, disconnection).

Scenario: Digital quantity expansion for PLC systems, controlling on/off timing of solenoid valve groups.

Process:

Scenario: Closed-loop control of motor speed and position.

Process: