RS-232C接口定义(DB9)

RS-232C接口定义(DB9)
 
引脚  定义  符号
1  载波检测  DCD（Data Carrier Detect）
2  接收数据  RXD（Received Data）
3  发送数据  TXD（Transmit Data）
4  数据终端准备好  DTR（Data Terminal Ready）
5  信号地  SG（Signal Ground）
6  数据准备好  DSR（Data Set Ready）
7  请求发送  RTS（Request To Send）
8  清除发送  CTS（Clear To Send）
9  振铃提示  RI（Ring Indicator）

DB9和DB25的常用信号脚说明;RS232接口针脚定义(2008-08-20 16:24:21)




标签：杂谈
分类：电子专业
9针接口针脚定义
Pin 1 Received Line Signal Detector (Data






说明：实际开发接口时，一般只要2，3，5，即收、发和地三根线，就能实现通信。
Carrier Detect)
Pin 2 Received Data
Pin 3 Transmit Data
Pin 4 Data Terminal Ready
Pin 5 Signal Ground
Pin 6 Data Set Ready
Pin 7 Request To Send
Pin 8 Clear To Send
Pin 9 Ring Indicator
RS232接口针脚定义
25针的接口定义：
Pin 1 Protective Ground
Pin 2 Transmit Data
Pin 3 Received Data
Pin 4 Request To Send
Pin 5 Clear To Send
Pin 6 Data Set Ready
Pin 7 Signal Ground Pin 8 Received Line Signal Detector
(Data Carrier Detect)
Pin 20 Data Terminal Ready
接线说明
1.DB9和DB25的常用信号脚说明
　9针串口（DB9） 25针串口（DB25）


针号功能说明 缩写 针号功能说明 缩写
1 数据载波检测 DCD 8 数据载波检测 DCD
2 接收数据 RXD 3 接收数据 RXD
3 发送数据 TXD 2 发送数据 TXD
4 数据终端准备 DTR 20 数据终端准备 DTR
5 信号地 GND 7 信号地 GND
6 数据设备准备好 DSR 6 数据准备好 DSR
7 请求发送 RTS 4 请求发送 RTS
8 清除发送 CTS 5 清除发送 CTS
9 振铃指示 DELL 22 振铃指示 DELL
2.RS232C串口通信接线方法（三线制）
9针－9针 25针－25针 9针－25针
　2 　3 　3 　　2 　　2　 2
　3 　2 　2 　　3 　　3 　3
　5 　5 　7 　　7 　　5　 7
RS-232接口


　　RS-232串行接口标准
　　目前RS-232是PC机与通信工业中应用最广泛的一种串行接口。RS-232被定义为一种在低速率串行通讯中增加通讯距离的单端标准。RS-232采取不平衡传输方式，即所谓单端通讯。
　　图1
　　收、发端的数据信号是相对于信号地，如从DTE设备发出的数据在使用DB25连接器时是2脚相对7脚（信号地）的电平，DB25各引脚定义参见图1。典型的RS-232信号在正负电平之间摆动，在发送数据时，发送端驱动器输出正电平在+5～+15V，负电平在-5～-15V电平。当无数据传输时，线上为TTL，从开始传送数据到结束，线上电平从TTL电平到RS-232电平再返回TTL电平。接收器典型的工作电平在+3～+12V与-3～-12V。由于发送电平与接收电平的差仅为2V至3V左右，所以其共模抑制能力差，再加上双绞线上的分布电容，其传送距离最大为约15米，最高速率为20kb/s。RS-232是为点对点（即只用一对收、发设备）通讯而设计的，其驱动器负载为3～7kΩ。所以RS-232适合本地设备之间的通信。其有关电气参数参见表1。

Interfacing with RS232 DB9 using Max233...


(1/1)


vputz:
Okay, reality check.  I'm interfacing my Arduino's pins 0 and 1 with another device running at 96008n1 using a Max233CPP driver.  The serial device takes its power from the serial port.  I'm trying to set up the port as DTE (as if it were a computer and I'm plugging this in as an input device)


I have, on the Max233:


Pins 17 and 12 connected (V-, maybe unnecessary)
Pins 15 and 11 connected (C+, seems to be necessary)
Pins 10 and 16 connected (C-, seems to be necessary)
Arduino Pin 0 (RX) to Max Pin 3 (R1out, for receiving RS232 as ttl)
Arduino Pin 1 (TX) to Max Pin 2 (T1in, for sending ttl as RS232)
Max pin 4 (R1in) to DB9 pin 2
Max pin 5 (T1out) to DB9 pin 3
DB9 pin 5 to ground
Max pin 14 (V+, should be +10v) to DB9 pins 4 and 7 (believe this is DTR/RTS)


Now, with one device it seems to work fine in that I can receive information no problem.  I have another device that is acting a little finicky in that I have to send it some setup bytes before it does anything.  I have a DIP switch such that I can control whether or not pins 0 and 1 are actually connected or not--this is so that I can disable pin 0 (recieve) and upload code via the USB connection and also disable pin 1 to the DB9 so that I can debug using Serial.print().


I'm just not sure if I'm actually sending bytes to the device--it SHOULD be beeping if it's working, and it's not.  Is there something obviously wrong with the wiring (particularly with regard to the power to DTR/RTS affecting flow control?)


Sorry, vexing problem for me (sending data to/from the device)


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