I have been trying to get a comfort controller(actually 3) to take a 4-20ma demand signal and change it directly to a 2-10v out for CWV & HWV of three identical AHU's. The demand is coming from another source that we cannot bypass. The "house" system gives demands only referencing the space temp. The CC6400 only sees the demand. We have supply and return sensors in place but they are not being used to control the system. Conventional wisdom says to let the CC6400 control the building, but the powers that be will not allow that. I have been working closely with the local Carrier technical support guy.( who is great to work with and a nice guy ) but we can't seem to get a direct input to out to the CWV , HWV AOut. We are using custom Ma in and the like , but seem to only be able to speed up and slow down the PID reacting to the demand signal. ANY IDEAS WOULD BE APPRECIATED. I know it would be easier to direct wire the demand to the valves with resisitor but then the safeties(esp. frzstat) would also have to be reworked and the issues could get bigger.