To obtain the temperature value from the DS18B20 sensor uses its own command-line utility, and configuration of zabbix agent described the challenge of this utilities like UserParameter. The temperature data in zabbix do this, but sometimes an error occurs that utility returns in the form of text and in this case, the item goes into state "not supported". When item status is "not supported", disabled triggers, including trigger {name_server:temper.nodata(5m)}=1 and I can't find out temperature monitoring or not. How to learn about the situation, when temperature data are not available in zabbix?