E1.20 RDM (Remote Device Management) Protocol Forums  

Go Back   E1.20 RDM (Remote Device Management) Protocol Forums > RDM Developer Forums > RDM Physical Layer/Hardware Discussion

RDM Physical Layer/Hardware Discussion Discussion and questions relating to the physical or hardware layer of RDM.

 
 
Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
Old February 18th, 2015   #1
markktoo
Junior Member
 
Join Date: Feb 2015
Posts: 1
Default RDM Line Bias - bus loading ambiguous

ANSI E1-20 2010 specifies line bias network for RDM. It indicates that the network will maintain bias when link is loaded with equivalent of 32 UL. Per Ti RS485 design guidelines http://www.ti.com/lit/an/slla272b/slla272b.pdf the bias network impacts the maximum number of unit loads. The recommended bias network reduces the maximum number of loads to 12. This is not clear in the standard and may imply that 32 ULs can be connected to the bus.

Fortunately many of today's transceivers are 1/4 or even 1/8 unit loads. With an 1/8 UL, up to 96 devices can be connected to the bus.

Perhaps this section of the RDM standard should be updated.
markktoo is offline   Reply With Quote
 

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Line biasing Andy Macdonald RDM Physical Layer/Hardware Discussion 1 October 26th, 2006 11:02 AM


All times are GMT -6. The time now is 03:15 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.