In SX Microcontrollers, SX/B Compiler and SX-Key Tool, George Herzog wrote:

BPM,
I couldn't locate a schematic either.  I suspect that you need to insert a MAX-232 to get proper TTL with a good RS-232 interface.  I would keep the SX-key intact and just build a converter as you need to provide outside power.
 
The basics are that RS-232 is NOT TTL;  it should have a positive and a negative voltage of about 9 volts (but many manufacturers have been lax in providing those voltages as they require more parts); and also the RS-232 signals are inverted from the TTL.  So a TTL high would be a -9Volts.

---------- End of Message ----------


You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=133688#m133928

Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com

The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)