RS232, RS485, TTL conversion

Discussion in 'General Electronics Chat' started by rogerthatpsr, Nov 16, 2009.

  1. rogerthatpsr

    Thread Starter Member

    Aug 22, 2006
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    I want to convert both RS232 and RS485 to TTL.....ie the circuit should have provision for both RS232 n RS485.... how do i do it? are both converters available on same IC ? both should have different connectors or needs a single connector ( r pins same ? )(eg DB9) ???
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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  3. rogerthatpsr

    Thread Starter Member

    Aug 22, 2006
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    @ above... thank u sir, i went thru both of them but i prefer a single IC due to power n spacing constraints....

    i want both RS232 & RS485 interfaces (half duplex would be ok) one at a time (not simultaneous) to be converted to TTL level so that i can interface it to MC .

    can MAX3160 this b used for the above application ...i've attached a blk diagram of it...if not this wat abt MAX3161 ? i went thru the datasheet but was too confusing....can anybody help ?
     
  4. Papabravo

    Expert

    Feb 24, 2006
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    As I read the datasheet the MAX3160 can be one or the other but not both. The choice is made by hard strapping to GND for RS232 and VCC for RS-485. It is inconceivable that you would want to risk having this pin switchable. See diagram on p. 10.

    The diagram on p. 11 for the MAX3161 shows the same behavior where pins can be either RS232 or RS-485 but not both simultaneously. Again hard strapping is the configuration method and I can't imagine doing it another way without significant risks.

    The MAX3162 has the proper number of pins to support separate external interfaces to both RS232 and RS-485 according to the picture on p.12

    If you intend to operate your device with either RS-232 or RS-485 but not both from a single UART then the multiplexing and demultiplexing can be done once the signals are at logic levels, and furthermore if your application requires it, you can use a microcontroller port pin to select which interface you will be using. In this case all physical layer problems can be delt with and there is minimal risk of connecting the wrong thing to your interface connectors assuming they are physically different e.g. RJ11 and DB-9.

    Be prepared to open your wallet, cuz 28 pins for an interface part is a battleship.
     
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