[Apcupsd-users] modbus unstable?

[Andras G. <an...@ga...>]

Hi,

I am running apcupsd on a dedicated rpi 3B, running ubuntu server 22.04.2 which is connected to an SMT1500i using USB.
Apcupsd is configured to use modbus communication with the UPS.

The communication is working fine, but every few days (between 1-4) it seems to have a hiccup and start sending outdated data: when this happens, the DATE field in apcaccess' response stays the same and no fresh data is displayed. I am getting no errors displayed or logged.

I started logging the "age" of information:

[A graph with green lines  Description automatically generated]

Restarting the pi seems to resolve the issue. I have already replaced the USB cable (now using a very short high-quality cable)

Is there any trick to get the communication to be more reliable?

Thanks,
András