工程师 - RS232 cable布线种类

RS232连接线分类：交叉还是直连

RS232 cable (wiring for Crossed/Straight)

工业中使用两种典型的 RS232 电缆。

* 交叉 RS232 电缆（或称为 null 调制解调器电缆）

* 直式 RS232 电缆

RS232 的交叉电缆布线通常发生在两个 DCE（数据通信设备）设备或两个 DTE（数据终端设备）设备之间。

There are two typical RS232 cables used in the industrial.

* Crossed RS232 cable (or known as null modem cable)

* Straight RS232 cable

Cross cable wiring for RS232 usually happens between two DCE (data communication equipment) devices, or two DTE (Data Terminal Equipment) devices.

RS232 cable分为直连和交叉，直连的话按对应位置，信号线一一连接。交叉的话，RX/TX交叉，RTS/CTS交叉，在cable里完成信号线交叉。

这样两端的设备，就能够一方的RX接到对方的TX，一方的RTS接到对方的CTS。

这种交叉的cable，两端的头就应该都是公头或都是母头。

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RS-232 电缆可以是交叉（null modem）电缆，也可以是直通电缆，具体取决于应用：

1、直通式 RS-232 电缆： 用于连接数据终端设备（DTE）和数据通信设备（DCE），如计算机和调制解调器。在此配置中，引脚一对一连接（例如，引脚 2 连接引脚 2，引脚 3 连接引脚 3 等）。

2、交叉（空调制解调器）RS-232 电缆： 用于直接连接两个 DTE 设备，如一台计算机连接另一台计算机。在这种配置中，发送线和接收线是交叉的（例如，针脚 2 连接针脚 3，针脚 3 连接针脚 2）。

因此，电缆是直式还是交叉式取决于你要连接的设备。

RS-232 cables can be either crossover (null modem) or straight-through, depending on the application:

1, Straight-Through RS-232 Cable: Used for connecting Data Terminal Equipment (DTE) to Data Communications Equipment (DCE), such as a computer to a modem. In this configuration, the pins are connected one-to-one (e.g., pin 2 to pin 2, pin 3 to pin 3, etc.).

2, Crossover (Null Modem) RS-232 Cable: Used for connecting two DTE devices directly, like a computer to another computer. In this configuration, the transmit and receive lines are crossed (e.g., pin 2 to pin 3, pin 3 to pin 2).

So, whether the cable is straight or crossover depends on the devices you are connecting.

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为了实现 DTE 和 DCE 之间的串行通信，有两种 RS232 电缆。它们是空调制解调器电缆和直电缆。在空调制解调器电缆中，公连接器的 TX（发送器）引脚与母连接器的 RX（接收器）引脚相连，公连接器的 RX 引脚与母连接器的 TX 引脚相连。

To make serial communication possible between DTE and DCE, two types of RS232 cables exist. They are Null modem and Straight-cable. In null modem cable, the TX (Transmitter) pin of the male connector is linked up with the RX (Receiver) pin of the female and the RX pin of the male is connected to TX pin of the female.

下一种是直通电缆。顾名思义，这是一种一对一的连接器，即一个设备的发送引脚连接到另一个设备的发送引脚，一个设备的接收引脚连接到另一个设备的接收引脚。除连接外，电缆长度还取决于布线电容。根据规格，电缆长度接近 80 英尺。

Next one, is the Straight-through cable. As the name implies, it is a one to one connector, i.e. a transmit pin of one device is connected to transmit pin of another device and receiver pin of one device is connected to receiver pin of another device. Apart from connections, the cable length depends upon the wiring capacitance. As per specification, the cable length is nearly 80 feet.