请问RS485通信，7M速率时，电缆线最长可多少?

只看该作者 · 2009-4-14 19:59

如果用SP491，需要接多大的电阻。

1万 · 2009-4-14 21:52

详细请进入：http://blog.21ic.com/more.asp?name=iC921&id=9466

［035］	［035］
Simple charts are used to help the user select the proper cable without any technical understanding of the cable parameters. This program divides the usage categories into EIA-232-D, EIA-422-A, and EIA-423-A. When using this literature, use the EIA-422-A charts for choosing RS-485 cable.	简单的曲线图可以帮助用户不需要任何电缆参数和技术认识情况下选择性能适宜的电缆。This program按用途分成三类：EIA-232-D、 EIA-422-A和EIA-423-A。用这些文献时，可用EIA-422-A的曲线图来选择RS-485电缆。

Figure 3.1: Data Signalling Rate versus Cable Length for Balanced Interface Using 24 AWGTwisted pair Cable

Note 1: Above attenuation data is supplied courtesy Belden Wire and Cable Company
Note 2: Datalene is a registered trademark of Belden Wire and Cable Company. Datalene is a type of foamed cellular polyethylene insulation.
Figure 3.2: Attenuation versus frequency for several Data Cable