I acquired a new job with a Automated Logic System using BACnet MS/TP to communicate over a PTlink to some Wattmaster VCM controllers. There are two controllers on the network. I guess ever since day one they have been having some issues. The RTUs will intermittently shut down due to the units seeing a 0 degree discharge air temperature. I have trended all of the different points out of the units on the BACnet side of things. I can see a few of the points go to 0 at the same time. The thing is the units are actually responding to this 0 and going off on freeze. So the fans shut down until the sensor shows valid again. I can hook up to the wattmaster VCM controllers and multiple points are reading 0. It does this on all of the controllers randomly throughout the day. I can I track down what is causing this problem. I don't know if it is some sort of network problem on the BACnet side of things and points are getting written to the units that shouldn't be. I have contacted wattmaster and they are thinking it may be there controllers, but I am not sure if that is true or not. What kind of things can I check to try to track down this issue?