Bandwidth Allocation Strategy for HDMI/DP Interfaces in Industrial Fanless PC Multi-Screen Display Output at 4K Resolution

Introduction: Core Challenges of Industrial Multi-Screen Display
In industrial scenarios such as smart manufacturing, energy monitoring, and intelligent healthcare, multi-screen display has become a key technology for enhancing operational efficiency and achieving data visualization. For instance, a monitoring center in a photovoltaic power plant needs to simultaneously display the operating status of inverters, grid load curves, and meteorological data, which cannot be met by a single screen in terms of real-time monitoring requirements. Similarly, a quality inspection station on an automobile production line requires multi-screen comparison of vehicle parameters with standard models to ensure production quality. However, under 4K resolution (3840×2160), multi-screen display imposes stringent requirements on interface bandwidth, signal stability, and hardware compatibility. This article delves into the bandwidth allocation strategies of HDMI and DP interfaces in 4K multi-screen scenarios and explores how the Industrial Fanless PC USR-EG628 addresses industry pain points through hardware optimization and protocol support.

1. Bandwidth Requirements and Interface Bottlenecks for 4K Multi-Screen Display

1.1 Bandwidth Calculation Model for 4K Resolution

• HDMI 2.0: A single interface can drive a single 4K@60Hz screen. Multiple screens require bandwidth allocation through multiple interfaces, but the total bandwidth is limited (e.g., 36 Gbps required for two screens, exceeding the HDMI 2.0 limit).
• DP 1.4: Through MST technology, multiple screens can be daisy-chained. For example, a single DP interface can drive two 4K@60Hz screens (with DSC compression enabled) or three 4K@30Hz screens (without compression).
• DP 2.0 (Future Trend): Supports 80 Gbps bandwidth, easily enabling a single interface to drive four 4K@60Hz screens, but its current prevalence in industrial equipment is low.

2. Bandwidth Allocation Strategies for Multi-Screen Display

2.1 Strategy 1: Independent Interface Allocation (Uncompressed)

Applicable Scenarios: Industrial control scenarios sensitive to latency, such as visual guidance for robotic arms.
Implementation Method:
Each 4K display is connected to an independent DP or HDMI interface to avoid bandwidth sharing.
For example, the USR-EG628 Industrial Fanless PC is equipped with 2 DP 1.4 interfaces and 1 HDMI 2.0 interface, capable of simultaneously driving three 4K@60Hz screens (with DSC compression disabled).
Advantages: Uncompressed transmission ensures image quality with a latency of less than 5 ms.
Limitations: The graphics card must provide sufficient physical interfaces, resulting in higher costs.

2.2 Strategy 2: DP MST Multi-Stream Transport (Compressed/Uncompressed)

Applicable Scenarios: Static content display in monitoring centers and data dashboards.
Implementation Method:
Through the MST function of DP 1.4, a single interface signal is split into multiple outputs.
For example, driving two 4K@60Hz screens with a single DP interface:

• Uncompressed mode: The total bandwidth required for the two screens must be ≤ 25.4 Gbps (actual requirement: 12.44 Gbps × 2 = 24.88 Gbps, close to the limit).
• DSC compression mode: Visual lossless compression reduces bandwidth requirements by 50%, allowing a single interface to stably drive two 4K@60Hz screens.
• Advantages: Reduces the number of cables and lowers costs.
• Limitations: DSC compression requires display support and may introduce minimal latency (< 1 ms).

2.3 Strategy 3: Hybrid Interface Combination (DP + HDMI)

Applicable Scenarios: Transitional scenarios requiring compatibility with old and new standards.
Implementation Method:
The main screen (dynamic content) uses a DP interface, while the secondary screen (static data) uses an HDMI interface.
For example, the DP interface of the USR-EG628 drives the main screen at 4K@120Hz (requiring DP 1.4 + DSC), while the HDMI interface drives the secondary screen at 4K@60Hz (HDMI 2.0).
Advantages: Balances performance and cost with wide compatibility.

Limitations: Manual management of refresh rates and color depths for different interfaces is required.

EG628

Linux OSFlexibly ExpandRich Interface

3. Bandwidth Optimization Practices of the USR-EG628 Industrial Fanless PC

3.1 Hardware Architecture Design

The USR-EG628 adopts an RK3568 quad-core ARM Cortex-A55 processor, integrating a Mali-G52 GPU and a 1 TOPS NPU. Its display output module features the following:

• Interface Configuration: 2 × DP 1.4 + 1 × HDMI 2.0 + 1 × LVDS, supporting simultaneous driving of four screens.
• Bandwidth Management: Built-in hardware DSC encoder for real-time compression of DP output signals, reducing bandwidth requirements by 60%.

Protocol Support: Compatible with VESA DisplayPort Alt Mode, enabling expansion of a fifth screen via a USB-C interface (with an adapter).

3.2 Multi-Screen Scenario Cases

Case 1: Photovoltaic Power Plant Monitoring Center

• The DP1 interface of the USR-EG628 drives two 4K@60Hz screens via MST (with DSC compression enabled).
• The DP2 interface drives the third 4K@60Hz screen (uncompressed).
  Total Bandwidth Requirement: 12.44 Gbps (DSC for two screens) + 12.44 Gbps (uncompressed for one screen) = 24.88 Gbps < the 50.8 Gbps limit of DP 1.4 × 2.
  Effect: Achieves zero-latency data refresh and reduces fault response time to 200 ms.
  Case 2: Quality Inspection Station on an Automobile Production Line
  Requirements: Two 4K@120Hz screens for comparing vehicle parameters with 3D models.
  Solution:
• The DP1 interface of the USR-EG628 drives the main screen at 4K@120Hz (DP 1.4 + DSC).
• The HDMI interface drives the secondary screen at 4K@60Hz (HDMI 2.0).
  The NPU accelerates 3D model rendering, reducing GPU load by 30%.
  Effect: Improves quality inspection efficiency by 40% and reduces the false detection rate to 0.5%.

4. Industry Solution and Selection Recommendations

4.1 Key Selection Indicators

4.2 Core Advantages of the USR-EG628

• Cost-Effectiveness: Compared to x86 industrial computers, the ARM architecture reduces power consumption by 60% and lowers the total cost of ownership (TCO) by 40%.
• Flexible Expansion: Supports PCIe expansion cards for integrating 4G/5G modules for remote monitoring.
• Ecosystem Compatibility: Pre-installed with Renyun Platform, supporting multi-screen data synchronization and remote management.

5. Stepping into a New Era of High-Bandwidth Industrial Display

With 4K multi-screen display becoming an industrial necessity, bandwidth allocation strategies must balance performance, cost, and compatibility. The USR-EG628, through DP 1.4 + DSC technology, multi-interface collaborative design, and edge computing optimization, provides a highly reliable and low-latency multi-screen solution for smart manufacturing, energy management, and other fields.

Take Action Now: Contact PUSR to obtain a customized configuration plan for the USR-EG628, including:

• Multi-screen bandwidth allocation toolkit
• Industrial protocol compatibility test report
• 30-day free trial of a sample machine
  Let the USR-EG628 serve as your industrial display system's "bandwidth manager," unlocking the productivity potential of multi-screen displays!