Tuesday, 4 February 2014

RS232 and RS485 Comparative Study - Communication Protocols In Digital Electronics

RS232 and RS485 Comparative Study
RS232 Protocol

RS-232 is the most common serial interface and ships as a standard component on most Windows-compatible desktop computers. RS-232 only allows for one transmitter and one receiver on each line. RS-232 also uses a Full-Duplex transmission method

In Short:

  1. Unbalanced / non-differential (all same terms)
  2. Point to point
  3. No. of Drivers = 1
  4. No.of receivers =1
  5. Full duplex (so it can be half duplex also)
  6. Distance (Standard) = 15m
  7. Receiver input sensitivity( a valid signal) = +-3V
  8. Max speed at 12m = 20kbps
RS-485 Protocol
RS-485 is a superset of RS-422 and expands on the capabilities. RS-485 was made to address the multi-drop limitation of RS-422, allowing up to 32 devices to communicate through the same data line. Any of the slave devices on an RS-485 bus can communicate with any other 32 slave devices without going through a master device. Since RS-422 is a subset of RS-485, all RS-422 devices may be controlled by RS-485. 

In Short:

  1. Balanced. differential
  2. No.Drivers = 32
  3. No.of Receivers = 32
  4. Multi point
  5. Half duplex
  6. Distance (standard) = 1200m
  7. Receiver input sensitivity( a valid signal) = +-200mV
  8. Max speed at 12m = 35Mbps 
Video Tutorial:RS232 and RS485 Comparison

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