如何判断一个未知设备的波特率？ [复制链接]

手里有一个FEI出的GPS驯服钟，按照手册上说的是它有一个9针串口可以输出相关的数据并可以通过软件进行控制。但是现在的问题是，电缆连接应该没问题，软件也不报串口出错，但收不到任何的数据，也无法用软件的菜单控制这个设备。

我用串口调试助手连接这个设备，准备分析一下它的数据包。但是不知道它原来设置的波特率是多少，我用9600或者手册上建议的38400连接都可以收到有规律的报文。这种情况下如何判断设备工作的波特率呢？另外附图是我用示波器测量的该设备串口3针的信号，峰-峰幅度达到19V之多，这个正常吗？

附上一段抓取的报文：

38400波特率时：

Open serial port successfully
80 00 80 00 00 F8 00 00 00 00 00 00 00 00 00 00 00 00 00 F8 00 00 F8 78 3C F0 80 00 80 80 78 00 00 F8 00 00 78 C0 00 F8 00 80
00 78 FC 00 80 00 78 3C 00 78 00 00 80 F8 00 00 00 00 00 00 00 00 80 00 F8

80 00 80 00 00 F8 00 00 00 00 00 00 00 00 00 00 00 00 00 F8 00 00 F8 78 3C F0 80 00 80 80 78 00 80 F8 00 00 78 C0 00 F8 00 80
00 78 FC 00 80 00 78 3C 00 78 00 00 80 F8 00 00 00 00 00 00 00 00 00 80 F8

80 00 80 00 00 F8 00 00 00 00 00 00 00 00 00 00 00 00 00 F8 00 00 F8 78 3C F0 80 00 80 80 78 00 00 00 00 78 C0 00 F8 00 80 00
78 FC 00 80 00 78 3C 00 78 00 00 80 F8 00 00 00 00 00 00 00 00 80 80 F8

80 00 80 00 00 F8 00 00 00 00 00 00 00 00 00 00 00 00 00 F8 00 00 F8 78 3C F0 80 00
80 80 78 00 80 80 00 00 78 C0 00 F8 00 80 00 78 FC 00 80 00 78 3C 00 78 00 00 80 F8 00 00 00 00 00 00 00 00 00 78 FC

80 00 80 00 00 F8 00 00 00 00 00 00 00 00 00 00 00 00 00 F8 00 00 F8 78 3C F0 80 00
80 80 78 00 00 F8 00 00 78 C0 00 F8 00 80 00 78 FC 00 80 00 78 3C 00 78 00 00 80 F8 00 00 00 00 00 00 00 00 80 78 3C FF

-----------
9600波特率时：

Open serial port successfully
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 24 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 DB
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 26 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 DD
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 28 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 DF
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 2A 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 E1
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 2C 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 E3
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 2E 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 E5
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 30 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 E7
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 32 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 E9
02 02 00 03 00 00 00 00 00 00 00 00 00 00 00 00 07 BC 25 98 0B 34 00 00 09 07 02 0D 06 05 01 00 FA 00 00 00 00 00 00 00 00 EB

图片:PICOSYNC-II.png

拿示波器看信号最窄的脉冲对应的频率就是波特率了，232电平的峰峰值是可以到近二十伏的

内容来自Android手机客户端

zzzzy:拿示波器看信号最窄的脉冲对应的频率就是波特率了，232电平的峰峰值是可以到近二十伏的 (2012-08-28 18:19) 

谢谢指点。刚才测试了一下，最窄的脉冲大约100us，这样算的话，波特率大概是(0.1ms*10bit)=10bit/ms=10000/s，大概是9600波特率，不知道这样计算是否正确？

是9600的波特率，老外网站早就有数据了，不过有很大部分还没破解。

BG7TBL:是9600的波特率，老外网站早就有数据了，不过有很大部分还没破解。 (2012-08-28 20:55) 

是说这个驯服钟吗？能给个链接看一下吗？谢谢。

显示成ascii码看看！