I got into UPB several months back with an IO module then a pair of wall switches. I had very reliable operation and was very happy with the signal and noise test capability that was built-in. A few months back my IO module stopped working most of the time. It was installed in an unheated damp building so I attributed it to the winter climate change. Simply Automated was responsive and gave me a another IO module.
In the following week I lost communication with my two switches. Upstart could not even see them when running comm tests. SA sent me another PIM and another switch. With some off and on testing I observed that sometimes I could see all three modules, sometimes I could see the two switches, and sometimes none. When they would respond the signal strength was always very good at both the PIM and device with typical vales of 80 to 100. Noise levels have always been 0. Note that during this entire evaluation period the IO module was plugged directly into the PIM.
Since the problem did not appear to be UPB hardware I went down the process of elimination route by cutting breakers and moving devices among circuits. Nothing I did would make all three devices respond but a fraction of the time duirng a comm test.
An observation that I did not expect was the use of a 5A X10 filter caused the IO module to be never seen. Nothing was connected to the X10 filter. Just its presence on the circuit would stiffle the IO. Another observation is that one of the switches (UB2-40) would be detected to be setup mode (when manually place in setup mode) and program without difficulty, but once programmed it would rarely be visible in the comm test.
Something has changed over the past few months and the change may be at a neighbor's house. It might be at mine, but I certainly dont know what it may be. I'm still working with SA to try to get to the bottom of it. Had I not had good operation for many months then I would be more suspect of my install, but this is something that was working great then quickly degraded.
It is frustrating, but the worst part is that the built-in diagnostics are of no help with the isolation of the problem.