INDUSTRY COMPONENT

Request Queue

A request queue is a digital buffer in a bus arbiter that manages and prioritizes access requests from multiple devices to a shared communication bus.

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Component Specifications

Definition
In industrial automation and embedded systems, a request queue is a critical component of a bus arbiter that temporarily stores and sequences access requests from various peripherals, processors, or subsystems competing for the shared bus. It implements scheduling algorithms to determine the order of service, ensuring efficient data transfer and preventing conflicts in multi-master bus architectures like PCI, CAN, or industrial Ethernet.
Working Principle
The request queue operates by receiving and storing incoming access requests in a first-in-first-out (FIFO) or priority-based buffer. The arbiter evaluates these requests based on predefined rules (e.g., fixed priority, round-robin, or time-sensitive networking) and grants bus access to the highest-priority request. Once serviced, the request is removed from the queue, and the next request is processed, minimizing bus idle time and maximizing throughput.
Materials
Typically implemented in silicon as part of an integrated circuit (IC) using semiconductor materials like silicon, with digital logic gates and memory cells (e.g., SRAM or flip-flops). No external materials are involved.
Technical Parameters
  • Queue Depth 8 to 256 entries
  • Bus Interface PCIe, CAN, Ethernet, SPI, I2C
  • Clock Frequency Up to 200 MHz
  • Power Consumption < 100 mW
  • Arbitration Algorithm Fixed Priority, Round-Robin, Weighted Fair Queuing
  • Operating Temperature -40°C to 85°C
Standards
ISO 11898, ISO 26262, IEC 61131, IEEE 802.3

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Request Queue.

request queue bus arbiter industrial automation electronic control priority scheduling FIFO buffer multi-master bus PCI arbitration CAN bus embedded systems Request Queue in Computer, Electronic and Optical Product Manufacturing

Parent Products

This component is used in the following industrial products

Bus Arbiter

A hardware component within a Bus Interface Unit that manages access to a shared bus by multiple devices or processors.

View Product Details

Memory Arbitration Unit

A hardware component within a Graphics Interface Controller that manages and prioritizes memory access requests from multiple sources.

View Product Details

Engineering Analysis

Risks & Mitigation
  • Queue overflow leading to data loss
  • Priority inversion causing system deadlock
  • Timing violations in high-speed operations
FMEA Triads
Trigger: Insufficient queue depth for high traffic
Failure: Request overflow and data corruption
Mitigation: Implement dynamic queue resizing or flow control mechanisms
Trigger: Faulty arbitration logic
Failure: Unfair bus access or system hang
Mitigation: Use redundant arbiters and periodic self-test routines
Trigger: Clock signal instability
Failure: Timing errors in queue operations
Mitigation: Employ phase-locked loops (PLLs) and robust clock distribution networks

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Signal timing tolerance within ±5% of clock period, voltage levels compliant with bus specifications
Test Method
Functional testing via simulation and hardware-in-the-loop (HIL) testing, compliance with industry bus standards

Buyer Feedback

★★★★☆ 4.6 / 5.0 (32 reviews)

"Found 38+ suppliers for Request Queue on CNFX, but this spec remains the most cost-effective."

"The technical documentation for this Request Queue is very thorough, especially regarding technical reliability."

"Reliable performance in harsh Computer, Electronic and Optical Product Manufacturing environments. No issues with the Request Queue so far."

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Frequently Asked Questions

What is the primary function of a request queue in a bus arbiter?

The primary function is to manage and prioritize multiple access requests to a shared bus, ensuring orderly and efficient data transfer without conflicts.

How does a request queue improve system performance?

It reduces bus contention and idle time by scheduling requests optimally, leading to higher throughput and lower latency in communication between devices.

Can request queues be customized for specific applications?

Yes, queue depth, arbitration algorithms, and priority schemes can be tailored to meet the real-time requirements of specific industrial applications.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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