无源 USB 延长线最长就是5米 别折腾了

本帖最后由 vodka 于 2009-5-15 00:50 编辑

引用: 我现在用的是八米的延长线.sj904 发表于 2009-5-15 00:36

你的8米线能保证什么速?  代价呢?        5m 成品的 UL/CSA认证的 USB 2.0 延长线是 人民币 8~15 元,  带 HUB 芯片的品牌线是 45~100 元         用最便宜的带HUB芯片的有源线5条+ 5m 无源线延长到 30 米的花费是 200 元左右,  可以保证 USB 2.0 全速         =====================Maximum useful distanceUSB 1.1 maximum cable length is 3 metres (9.8 ft).[15] USB 2.0 maximum cable length is 5 metres (16 ft). Maximum hubs connected in series is 5. Maximum devices connected in total is 127.Although a single cable is limited to 5 metres, the USB 2.0 specification permits up to five USB hubs in a long chain of cables and hubs. This allows for a maximum distance of 30 metres (98 ft) between host and device, using six cables 5 metres (16 ft) long and five hubs. In actual use, since some USB devices have built-in cables for connecting to the hub, the maximum achievable distance is 25 metres (82 ft) + the length of the device's cable.USB 3.0 does not define cable assembly lengths, except that it can be of any length as long as it meets all the requirements defined in the specification. However, electronicdesign.com estimated that cables will be limited to 3 metres at top speed.[16]Since USB provides power for devices connected to the bus, a special type of USB extender cable was created, consisting of a miniature one-port USB hub molded onto one end of a 5-metre cable. These mini-hubs are fully self-contained within the cable, requiring no separate bulky hub device and no external power. They are as simple to use as plugging cables together, with each hub drawing power through all the previous single-port hubs in the chain. Because bus power is limited, the most practical arrangement consists of four single-port hub extender cables, one plain 5-metre cable and, at the very end, a powered multiport hub to support multiple USB devices.http://www.usb.org/developers/usbfaq/I really need to put a USB device more than 1000 meters away from my PC. What should I do?Answer:   Build a USB bridge that acts as a USB device on one side and has a USB host controller at the other end. Use a long-haul signaling protocol like Ethernet or RS-485 in the middle. Using cables or short-haul fiber, you can get ranges upwards of a kilometer, though there's no reason why the long-haul link in the middle of the bridge couldn't be a pair of radio transceivers or satellite modems.Embedded host solutions capable of doing this already exist. Also, two PCs connected via USB Ethernet adapters are essentially a slave/slave version of this master/slave bridge. 本文地址:http://forum.anywlan.com/thread-24265-1-1.html