I am using NUT to monitor my UPS. I have a APC Back-UPS ES 550G, and the NUT server runs on a Raspberry Pi. I use the usbhid-ups driver, which works fine most of the time. However, after a few hours of running, it starts to broadcast messages on the network that the UPS is not available, and any attempted queries will return "Data stale". Restarting the driver and the server solves the problem, at least for the next few hours.
I tried adjusting timing settings, but it doesn't seem to help. Currently I have the following settings: on the driver, pollfreq = 5 and pollinterval = 2. In the monitor config, I have POLLFREQ 5, POLLFREQALERT 5 (these are the defaults), and DEADTIME 30.
