rs232

RS232 is a serial communication system which is used to communicate between two devices. . RS stands for recommended standard. In recent years this suffix has been replaced with EIA/TIA232.

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RS232

RS232 is a serial communication system which is used to communicate between two devices. This standard has been introduced by ELECTRONICS INDUSTRY ASSOCAITION AND TELECOMMUNICATION INDUSTRY ASSOCIATION. RS stands for recommended standard. In recent years this suffix has been replaced with EIA/TIA232. 

WHY IT IS USED

  1. AUTOMATION
  2. COMPUTER SYSTEM
  3. NETWORK
  4. DRIVER CIRCUIT
 

PIN DIAGRAM

 

  • Most commonly RS232 is using DB25 connector but it has replaced to DB9 connector
  • In DB9 connector 9 pins will be there but we are using only three pins commonly
  • That is 2,3,5 RXD ,TXD ,GND

PIN DETAILS

Transmission data (TD): This is a signal which is send DTE (Data terminal equipment) by and received by DCE (data circuit-terminating equipment)

Received data (RD): It is the receiving of data which has send by DTE

Request to send: After getting RTS signals from DCE only DTE starts to send the data

Clear to send (CTS): CTS is a hand shaking signal between DTE AND DCE. Which is starting with RTS. It is used make sure that device is ready to receive data

DATA SET RADY (DSR): This signal is turned on bye DCE to indicate that it is connected to a telecommunication line 

DATA CARRIER DIRECT: This signal Is turned, DCE to indicate receiving signal from a remote DTE which meets its suitable signal criteria. This signal remains on as long as the suitable carrier signal can be detected.

DATA TERMINAL READY: DTR indicate the readiness of the DTE.This signal is turned on by the DTE when it is ready to transmit or receive data from the DCE.DTR must be on before DCE can assert DSR

RING INDICATOR: This signal is used to indicate the ringing signal is receiving on the communication channel.   

 

COMMUNICATION

In RS232 maximum data rate is 20kbit/s. so it I too slow for today’s application. But Dallas semiconductor is offering 250kbit/s and communication speed is depends on the cable length. RS232 can communicate up to 50 meter. But it is not using for long data transmission because of slow speed.

  • Through RS232 we can communicate only between two devices. It follows point to point communication system. For communicating two devices there will be a communication parameters it should be the same.
  • Bits per second(110 to 921600)
  • Number of data bits(8)
  • Parity (Mark, Space ,Odd ,even)
  • Number of Stop bits(1,1.5,2)

 

TRANSMISSION OF DATA

  • It encoding bits in to energy and sending the energy through medium and another device will decode energy to bits.
  • Transmitter and receiver must agree on encoding scheme and transmission timing
  • It commonly uses 8bit data
  • Energy can be electric current ,radio waves
  • Transmission and receiving speed should be same otherwise transmission will fail

 

Start BIT AND STOP BIT

  • The start bit is a logical 0 sent on the line to tell the other device to start sampling.
  • The logical 0 is +15VDC
  • The stop bit is using to tell to the other device to stop sampling \
  • A logical 1 is -15v

 

POINT TO POINT COMMUNICATION

Point to point is the communication technology which is followed by RS232.As the name itself it transfer data to one point to another .In this one master and one slave only will be there. Master will send the data to salve and slave will receive data. One time one side communication is possible otherwise whole transmission fails

 

DUPLEX, SIMPLEX OPERATION

  • AS same as RS485 232 also having full duplex and half duplex operation
  • Full duplex is used where  we want to send and receive data
  • Half duplex is used only one operation at time
  • Simplex is used for onside communication, there master is transmitting and receiver is always receiving

 

How it’s different from RS485

  • In RS232 communication speed is 20kbit/s to 250kbit /s bust in rs485 it is 100kbit/s to 35mbit/s
  • Communication distance in RS232 is 50m maximum but in RS 485 is 1200m
  • The RS232 can communicate only between two device but in RS485 it is up to 255 devices
  • Both are not specifying connectors
  • RS232 is using 0v to 15v, in the case of RS485 it is 0v to 5v

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