I will try to explain this the best I can. I have a building automation system that monitors air quality to turn on/off a fresh air exhaust system. The air quality sensors that were purchased for the job are a loop powered 4-20ma signal. The inputs to the automation system can be configured to 0-5v or 0-10v also. The problem that I have is that in the old sensors 20ma would equal good air quality and 4ma bad. The new sensors are opposite 4ma good quality 20 ma bad. In the automation program it uses an equation such as setpoint less than X activate system. I do not have the software program to make any changes to the system (setpoint greater than X activate system) is what I need. I cant simply reverse the polarity of the sensor because it is loop powered. Any ideas ?