ADLINK PCI-7200 High Speed Digital I/O Card

4. REQ/ACK hardware handshake mode

Bidirectional hardware response, board and external device synchronization:

Input process: Send an external I-REQ → Lock data on the board → Return an I-ACK;

Output process: DMA loads DO → board sends OREQ → receives OACK and refreshes the next group;

The only transmission mode that can guarantee 12MB/s without loss, preferred for high-speed scenarios.

Time sequence specification

The manual provides the minimum holding time for high and low levels of the I-REQ, O-REQ, handshake signal, and establishes/holds timing parameters. Hardware docking must meet the timing requirements.

Software Development Library

1. Platform differentiation

DOS: Pure C static library, function prefix _7200_;

Win95/98: DLL driver, function prefix W_7200_;

Support mainstream development tools such as VC, VB, Borland C, Delphi, etc.

2. Classification of API Functions

Board management

_7200Initialize the board, read the base address/interrupt; _7200_Switch_Card_Co multi card switching (up to 4 PCI-7200 cards);

Basic DI/DO Reading and Writing

Batch 32 channel read-write _7200-DI/_7200-DO; Single point read-write _7200-DI_Channel/_7200_DO_Channel;

CPCI exclusive auxiliary IO

_7200_ AUX DI/_ 7200_ AUX DO Batch/Single Channel 4-channel Auxiliary IO;

DMA memory management (exclusive to Windows)

Alloc_DMA_Mem single buffer, Alloc_DBDMA_Mem double loop buffer; Supporting the release of memory function;

DMA acquisition control

DI-DMA_Start starts input DMA and supports three types of triggers: timed/external/handshake; DI_SMA_Status query progress; DI_SMA_Stop stops;

DO_SMA_Start outputs DMA and supports timing/handshake;

Double buffer dedicated function

DblBufferMode enables loop buffering; CheckHalfReady half area data readiness judgment; DblBufferTransfer copies half of the data; GetOverrunStatus counts the number of overflow occurrences;

Timer configuration

DI_Timer configuration input frequency division; DO_Timer configuration output frequency division, supports single/cascade mode.

3. General programming process

Initialize board → Configure timer/trigger mode → Allocate DMA memory (high-speed scenario) → Start DMA transfer → Loop read/process data → Stop DMA and release memory.

Double buffer DMA principle

Only digital input supports circular double buffering:

The memory logic is divided into two equal half buffers;

Fill the first half of the hardware and switch to the second half after filling;

The application can synchronously read the filled half area, achieving uninterrupted continuous collection without data loss;

If the upper layer fails to read in a timely manner, overflow may occur, and the interface can be called to count the number of overflow occurrences.

Three major limitations on hardware usage

The theoretical peak of 12MB/s can only be achieved when a single PCI device monopolizes the bus, and the bandwidth decreases when multiple PCI devices coexist;

In internal/external triggering mode, due to limitations in FIFO depth and PCI bus delay, high-speed data integrity cannot be guaranteed, and only handshake mode stabilizes at 12MB/s;

The maximum single DMA transfer is 64MB (2 ^ 26 bytes), exceeding which segmented processing is required.

Appendix A: 8254 Timer Complete Information

3 independent 16 bit counters, 6 working modes (interrupt counting, monostable, rate generator, square wave, software/hardware gating pulse);

Control byte SC counter selection, RL read-write format, M working mode, BCD binary switching;

Timing and counting range of each mode (binary 0~65535, BCD 0~9999), used as a reference for timing beat generation.

Supporting tools, system support, and warranty

Supporting software: 7200UTIL testing tool, DOS C library Win95 DLL、 Example program;

Third party compatibility: LabVIEW and HP-VEE can be integrated through drivers;

Warranty: Original factory 1-year hardware warranty, no warranty for human modification or use beyond specifications.