In the process of developing an RDM Compatible DMX receiver board (using a ATMEGA328) and i have been fortunate enough to come across kimliv's most informative answer concerning such a board; 

http://electronics.stackexchange.com/questions/100487/dmx-on-arduino-with-rs485/100488#100488

However i was wondering why (if) it is necessary to use a TTL Compatible isolator? in this case the 6N317 or if perhaps a more traditional repeater isolator style circuit could be implemented using a more common and cheaper isolator for example the [H11A1][1] (which i just so happen to have in stock)

this all said it seems several DMX circuits i have come across utilise the 6N317 but so far as i am aware the transceiver ([MAX481][2]) could be used to drive other isolators. 

is there something obvious i am missing here? or anything in particular that makes the 6N317 quite so desirable for its use here? 

  
thank you. 

  [1]: http://docs-europe.electrocomponents.com/webdocs/1300/0900766b81300833.pdf
  [2]: http://docs-europe.electrocomponents.com/webdocs/1253/0900766b81253c33.pdf