What Is a Synchronous Control System?
A synchronous LED display system requires a continuous, real-time connection between the display and a host computer. The controller card inside the display receives video or image signals directly from a PC or media server, processes them frame by frame, and outputs the content simultaneously.
Key characteristics:
Requires a dedicated computer or media server running at all times
Displays content in real time - whatever appears on the source device is mirrored on the screen
Supports high-resolution video, live feeds, multi-zone layouts, and dynamic switching
Typical latency is under one frame (< 16 ms at 60Hz)
Common hardware: sending cards (e.g. Novastar, Colorlight) paired with receiving cards inside each cabinet
Typical applications: Stage performances, broadcast studios, sports venues, control rooms, high-end retail flagship stores, and any environment requiring live or frequently changing content.
What Is an Asynchronous Control System?
An asynchronous LED display system stores content locally on a memory card or internal flash storage within the controller itself. Once programmed, the display operates independently without needing a connected computer.
Key characteristics:
Content is uploaded in advance via USB, Wi-Fi, 4G, or Ethernet; the display then runs autonomously
No host PC required during operation
Supports images, video clips, text, and scheduled playlists
Resolution and content complexity are constrained by the controller's onboard memory and processing power
Lower hardware cost and simpler wiring
Typical applications: Standalone outdoor billboards, retail shelf-edge displays, transportation information boards, simple roadside signage, and any installation where content updates are infrequent.
| Parameter | Synchronous | Asynchronous |
|---|---|---|
| Content update method | Real-time from host PC | Pre-uploaded to local storage |
| PC required during operation | Yes | No |
| Latency | < 1 frame | N/A (no live feed) |
| Content complexity | High (video, live, multi-zone) | Moderate (images, video clips, text) |
| Hardware cost | Higher | Lower |
| Network dependency | Continuous | Upload only |
| Typical pixel pitch range | P0.9 – P6 (fine to medium) |
P4 – P20 (medium to large pitch) |
Hybrid Control: A Middle Ground
Some modern controller systems support both modes. During normal hours, the display runs pre-stored content asynchronously; when a live event occurs, an operator can switch to synchronous mode by connecting a laptop or streaming device. This flexibility is increasingly common in medium-sized outdoor advertising screens and semi-permanent rental installations.
Hybrid controllers reduce the need to purchase two separate systems, though they introduce additional configuration steps and require staff familiar with both modes.
Factors to Consider When Choosing
1. How often does the content change? If your content changes multiple times per day in real time (live news, stock tickers, camera feeds), a synchronous system is necessary. If you update content once a week or run a fixed playlist, asynchronous is sufficient.
2. Is a dedicated computer available on-site? Synchronous displays require a stable, always-on PC or media server. In remote locations - roadside cabinets, transit stops, rural billboards - this is often impractical without additional infrastructure.
3. What is the resolution and display size? High-resolution fine-pitch displays (P1.2 to P2.5) in control rooms or broadcast environments almost always use synchronous systems because the data throughput requirements exceed what most asynchronous controllers can handle.
4. What is the budget for hardware and maintenance? Asynchronous setups have lower upfront hardware costs, but synchronous systems offer greater content capability and are often more cost-effective when the display is a core part of a media or communication workflow.
Common Misconceptions
"Asynchronous means lower quality." Not necessarily. An asynchronous system can display high-quality pre-rendered video and images. The limitation is in real-time flexibility, not visual quality per se.
"Synchronous displays always need the internet." A synchronous system requires a signal connection between the display and the source device, but this can be a local HDMI or fiber link - an internet connection is not inherently required.
"Any controller card works with any LED module." Controller compatibility depends on the specific driver IC, scan configuration, and module protocol. Always verify that the sending card and receiving card are compatible with your cabinet's driver IC before procurement.
Summary
The choice between synchronous and asynchronous control is fundamentally about how content is delivered to the display and whether a host computer needs to be present. Neither system is inherently superior - the right choice depends on content frequency, installation environment, available infrastructure, and budget.
Understanding this distinction before purchasing an LED display system can prevent costly retrofits and ensure the final installation performs as intended.