I've been trying to figure out why Link 1 on an SC controls link keeps loosing communication for months. Breaks down for sometimes 30 minutes, sometimes days. I've broke the link in half and then slowly tried to narrow it to a unit or section of VAV's. I thought I had it down to a bad EOL device. I replaced both on each end of the Link, then watched it for almost 2 months work fine. Closed the work order and 3 weeks later they called back because it lost communication. There has got to be a better way of finding what's causing this. I can add more info with questions or responses. Thx