I have a Raspberry Pi with four DS18B20 sensors, using an rpi-ds18b20 node triggered at one minute intervals. The sensors are wired in parallel and use one 4K7 pull up on the data line. Their cable lengths are all less then 2m.
All is fine for some hours but then one, sometimes two of the sensors start displaying zero temperature either permanently or intermittently (not possible given where they are mounted). Re-starting the flow restores "normal" operation.
The same four sensors have worked reliably, monitoring the same physical entities, via an Arduino for some years.
I've tried changing the 3V3 for sensor power and data pull up for 5V power, 3V3 pull up.
I have tried swapping the rpi-ds18b20 node for the ds18b20 node.
Using 'cat /sys/bus/w1/devices/xyz/w1_slave' shows the correct sensor temperatures, a debug node shows the ds18b20 node outputting zeros.
Neither 'cat /var/log/syslog' nor 'node-red-log' show anything untoward.
Any suggestions would be much appreciated!