串行端口的引脚定义

硬件: Serial>>RS-485, Serial>>RS-485>>AT-485/2, Serial>>RS-485>>AT-485/2 NSI, Serial>>RS-485>>AT-485/4, Serial>>RS-485>>AT-485/4 NSI, Serial>>RS-485>>AT-485I/2, Serial>>RS-485>>AT-485I/4, Serial>>RS-485>>ENET-485/2, Instrument Connectivity Other>>Ethernet>>ENET-485/4, Serial>>RS-485>>PCI-485/2, Serial>>RS-485>>PCI-485/4, Serial>>RS-485>>PCI-485/8, Serial>>RS-485>>PCI-485I/2, Serial>>RS-485>>PCI-485I/4, Serial>>RS-485>>PCI-8431/2, Serial>>RS-485>>PCI-8431/4, Serial>>RS-485>>PCI-8431/8, Serial>>RS-485>>PCMCIA-485, Serial>>RS-485>>PCMCIA-485/2, Serial>>RS-485>>PXI-8421/2, Serial>>RS-485>>PXI-8421/4, Serial>>RS-485>>PXI-8421/8, Serial>>RS-485>>PXI-8423/2, Serial>>RS-485>>PXI-8423/4, Serial>>RS-485>>PXI-8431/2, Serial>>RS-485>>PXI-8431/4, Serial>>RS-485>>USB-485, Instrument Connectivity Other>>USB>>USB-485/2, Serial>>RS-485>>USB-485/4, Serial>>RS-232>>PCI-8430/8, Serial>>RS-232>>PCMCIA-232/2, Serial>>RS-232>>PCMCIA-232/4, Serial>>RS-232>>PXI-8420/16, Serial>>RS-232>>PXI-8420/2, Serial>>RS-232>>PXI-8420/4, Serial>>RS-232>>PXI-8420/8, Serial>>RS-232>>PXI-8422/2, Serial>>RS-232>>PXI-8422/4, Serial>>RS-232>>PXI-8430/2, Serial>>RS-232>>PXI-8430/4, Instrument Connectivity Other>>USB>>USB-232, Instrument Connectivity Other>>USB>>USB-232/2, Instrument Connectivity Other>>USB>>USB-232/4, Serial>>RS-232>>PCMCIA-232, Serial>>RS-232>>AT-232/2, Serial>>RS-232>>AT-232/2 NSI, Serial>>RS-232>>AT-232/4, Serial>>RS-232>>AT-232/4 NSI, Serial>>RS-232>>AT-232I/2, Serial>>RS-232>>AT-232I/4, Serial>>RS-232>>ENET-232/2, Serial>>RS-232>>ENET-232/4, Serial>>RS-232>>PCI-232/16, Serial>>RS-232>>PCI-232/2, Serial>>RS-232>>PCI-232/4, Serial>>RS-232>>PCI-232/8, Serial>>RS-232>>PCI-232I/2, Serial>>RS-232>>PCI-232I/4, Serial>>RS-232>>PCI-232I/8, Serial>>RS-232>>PCI-8430/2, Serial>>RS-232>>PCI-8430/4, Serial>>RS-232>>PCI-8432/2, Serial>>RS-232>>PCI-8432/4, Serial>>RS-485>>PCI-8433/2, Serial>>RS-485>>PCI-8433/4, Serial>>RS-232>>ExpressCard-8420/2, Serial>>RS-232>>PCI-8430/16, Serial>>RS-232>>PXI-8430/16, Serial>>RS-232>>PXI-8430/8, Serial>>RS-232>>PXI-8432/2, Serial>>RS-232>>PXI-8432/4, Serial>>RS-485>>ExpressCard-8421/2, Serial>>RS-485>>PXI-8431/8, Serial>>RS-485>>PXI-8433/2, Serial>>RS-485>>PXI-8433/4, Serial>>RS-232>>PCMCIA-232 921.6k, Serial>>RS-232>>PCMCIA-232/2 921.6k, Serial>>RS-485>>PCMCIA-485 921.6k, Serial>>RS-485>>PCMCIA-485/2 921.6k, Serial>>RS-485>>PXI-485/8, Serial>>RS-232>>PCI-8410/2, Serial>>RS-232>>NI 9870, Serial>>RS-485>>NI 9871

问题:
串口的引脚定义是怎样的? 用于loop back测试时需要连接哪些引脚?

解答:
RS-232是单端串行协议而RS-485 和 RS-422 是 差分的串行协议. RS-232, RS-422 和 RS-485 的引脚图如下.

 

loopback 测试是将信号从通信设备发出然后自己接收，用于测试设备是否工作正常 . 下图分别从RS-232 和 RS-422/RS-485三种情况给出了自发自收测试时哪些引脚需要连接.
RS-232

RS-422 和 RS-485

相关链接:
Developer Zone Example: Serial Loop Back Test for LabVIEW
KnowledgeBase 2WR9LNHW: How Do I Do a Loop Back Test with a 485 Port in Two Wire Mode?

附件:
DB-9Male.bmp
RS-232Loopback.bmp
RS-485_422Loopback.bmp

- Serial ports.bmp
- RS-232 loopback.bmp - RS-485 and 422 Loopback.bmp


报告日期: 04/24/2007
最近更新: 02/20/2009
文档编号: 48NB9TBH