in reply to: Re: Re: Ver 7 Compatability ver 5 CMD 0 posted by email@example.com on 07 September 2010 at 14:14:53.
Yes indeed, it's vital to work properly with older masters. For cases where it matters, the slave can tell the master revision from the data content of the command. For example, from a rev. 5 or 6 master, command 38 would have no data bytes (so the slave should reset the one of its two configuration changed flags relating to that particular master - primary or secondary); command 48 would have no data bytes, command 105 would have no data bytes, commands 108 and 109 would have only one data byte, and so on.
There are others. The rev. 7 command specs note such cases. Search for *backward compatibility requirements* in specs 127 and 151. A rev. 7 field device needs to follow the action specified in those documents.