(It would be nice if could email you directly (all my emails bounced)...)
I was lurking on the EMC IRC channel (mainly lurking because I cant figure out how to use my IRC client) and noticed you had a problem with the 3.3V outputs on the 5I20. The problem comes from driving an opto isolater powered from 5V with the 3.3V output of the 5I20, The opto isolator will have a ~1V IR LED forward drop meaning that even when off you have about .7V/R_series current going into the LED, leading to marginal operation. This is also a problem when used with I/O module racks with 5V input modules There is a very simple solution (which is in the 5I20 manual): Use the outputs as open drain, then they can swing all the way up to 5V when off (there are 3.3K pullups on the card). For the I/O configurations, this just means setting the assosciated output bits low, and outputing your signal via the Data Direction Register. I will add this capablity (open drain 5V outputs) as an option to the hardware step configuration. BTW I have made a non-buffered hardware stepgen configuration (free running DDS) with somewhat klunky but flexible dir-->step-->dir setup/hold timing. I will test it tommorow. Peter Wallace ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
