Intro to Serial Com port 介绍串行COM端口
RS232 DB9 Connector Pin Layout 的RS232 db9连接器引脚布局
RS232 DB25 Connector Pin Layout 的RS232 db25连接器引脚布局
DB25 Serial Convert to DB9 Connector db25串行转换为db9连接器
pins and wires 销和电线
RS232 RS422 RS485 Compare 的RS232 rs422 RS485的比较
Recommended RS232 Software 建议的RS232软件

- Intro to Serial port -介绍，以串行端口

The UART serial port (or just "serial Com port for short" is an I/O (Input/Output) device. 该UART的串行端口 （或只是“串行COM端口短期”是一个 I / O （输入/输出）设备。
An I/O device is just a way to get data into and out of a computer using. 1 I / O设备只是一个方法，获取数据的流入及流出的计算机上使用。 There are many types of I/O devices such as serial ports , parallel ports, disk drive controllers, ethernet boards, universal serial buses, etc. 有很多类型的 I / O设备，如串行端口 ，并行端口，磁盘驱动器控制器，以太网板，通用串行巴士，等等。

Most PC's have one or two serial ports.大多数PC的有一个或两个串行端口。 Each has a 9pin connector (sometimes 25pin) on the back of the computer.每有一个9pin连接器（有时25pin ）对计算机的背面。 Computer programs can send data (bytes) to the transmit pin (output) and receive bytes from the receive pin (input).电脑程式可以传送数据（字节） ，以传输引脚（输出）和接收字节从收到的PIN （输入） 。 The other pins are for control purposes and ground.其他引脚控制的宗旨和地面。
The serial port is much more than just a connector.串行端口是远不止只是一个连接器。 It converts the data from parallel to serial and changes the electrical representation of the data.它转换为数据的并行串行和变化，电气代表性的数据。 Inside the computer, data bits flow in parallel (using many wires at the same time).电脑内，数据位流的并行（使用许多电线在同一时间内） 。 Serial flow is a stream of bits over a single wire (such as on the transmit or receive pin of the serial connector).串行流是一个流位超过一个单一的电线（如对发送或接收引脚的串行连接器） 。

For the serial port to create such a flow, it must convert data from parallel (inside the computer) to serial on the transmit pin (and conversely).为串行端口建立这样一个流动的，它必须转换为数据的并行（电脑内）对串行传输的PIN （相反） 。

Most of the electronics of the serial port is found in a computer chip (or a part of a chip) known as a UART.大部分的电子串行端口，是发现在一块电脑晶片（或一部份晶片）众所周知，作为一个UART的。
For more details on UARTs see the section What Are UARTS?更多细节关于UART等，请参阅第UART等什么呢？ But you may want to finish this section first so that you will hopefully understand how the UART fits into the overall scheme of things.但您可能希望能在这里结束本节第一，这样，您就希望了解如何UART的适合纳入整体计划的东西。

- DB9 DB25 Pins and Wires -d b9d b25销和电线

Old PC's used 25 pin connectors but only about 9 pins were actually used so today most connectors are only 9pin. 旧PC使用的25插针连接器，但只有约9针，实际上使用的，所以今天大部分连接器只有9pin 。 Each of the 9 pins usually connects to a wire. 每年的9针，通常连接到电线。 Besides the two wires used for transmitting and receiving data, another pin (wire) is signal ground. 除了两个电线用于发射和接收数据，另一个针（丝）是信号的地面。 The voltage on any wire is measured with respect to this ground. 电压对任何丝，是衡量与尊重，以这个理由。

Thus the minimum number of wires to use for 2-way transmission of data is 3. 因此，最低数目的电线使用2双向传输的数据是3 。 Except that it has been known to work with no signal ground wire but with degraded performance and sometimes with errors. 除外，它一直在已知的工作与无信号地线，但与退化的表现，有时甚至有错误。 There are still more wires which are for control purposes (signalling) only and not for sending bytes. 还有更多的电线，这是为控制目的（讯号） ，而不是只发送字节。 All of these signals could have been shared on a single wire, but instead, there is a separate dedicated wire for every type of signal. 所有这些信号可以被共享一个单一的线，而是有一个单独的专用线，为每一类信号。 Some (or all) of these control wires are called "modem control lines". 部分（或全部）这些控制线被称为“调制解调器控制线” 。 Modem control wires are either in the asserted state (on) of +12 volts or in the negated state (off) of -12 volts. 调制解调器控制线无论是在断言国家（ on ）为12伏特，或在否定了国家（关闭） -12伏特。 One of these wires is to signal the computer to stop sending bytes out the serial port cable. 一，这些电线是信号的计算机停止发送字节指出串口电缆。 Conversely, another wire signals the device attached to the serial port to stop sending bytes to the computer. 相反，另一线的信号设备连接到串行端口停止传送字节到计算机中。 If the attached device is a modem, other wires may tell the modem to hang up the telephone line or tell the computer that a connection has been made or that the telephone line is ringing (someone is attempting to call in). 如果连接的设备是一台调制解调器，其他电线可能会告诉调制解调器挂断电话线或告诉的电脑连线已取得，或电话线是振铃（有人企图在通话） 。

- DB9 DB25 RS232 Wiring -d b9d b25的R S232线路