Running 3 PID loops with "T" type thermocouple inputs. 2 are positive loops, which are working as expected. The third needs to regulate below "zero". When my sensed temperature crosses the zero threshold into the negative region, my sensed temperature trends up -- when actual temperatures are really going down. I can mask and see the sign bit as working as expected. What do I do with it? How do I get my loop to regulate in the negative region? (works well now -- if I don't ask it to cross zero, i.e.: regulate at 10 deg. C.) Is there a general approach to the problem? Maybe a quick program example I can reference? I'll do the homework, just give me some direction. Thanks, ln