1. Technical Background
- RS-232: Traditional serial port standard, typical rate 115.2 kbps (maximum about 1 Mbps).
- RS-485: Industrial serial port standard, typical rate 10 Mbps (theoretical maximum can reach 50 Mbps).
- USB: There are significant differences between different versions, for example:
- USB 2.0:480 Mbps
- USB 3.0:5 Gbps (about 5120 Mbps)
- USB 4.0:40 Gbps
2. Comparison of USB and RS-232/RS-485 Rates
If the “232485” in your question refers to the combined term for RS-232 and RS-485, then the conversion ratios are as follows:
| Comparison Item | USB 2.0 (480 Mbps) | USB 3.0 (5 Gbps) | USB 4.0 (40 Gbps) |
|---|---|---|---|
| Equivalent to RS-232 Count | ≈ 4166 | ≈ 43,400 | ≈ 347,000 |
| Equivalent to RS-485 Count | ≈ 48 | ≈ 500 | ≈ 4,000 |
Calculation Formula:
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3. Differences in Practical Applications
- Protocol Overhead: USB requires additional processing of protocol layer data, with actual effective bandwidth about 70-90% of the nominal rate.
- Serial Port Limitations: RS-232/RS-485 is point-to-point communication, while USB supports multiple devices and high concurrency transmission.
- Scenario Differences:
- RS-232/RS-485: Low-speed scenarios such as industrial control and sensors.
- USB: Large file transfers and high-speed peripherals (e.g., SSDs, cameras).
