This monitors the temperature of an EX switch. Should work with other JUNOS devices as well. The MIB object polled is a table, and I have not found a way to get only one row in the table as output of the poller. However, you can edit the Universal Poller graph to only show row 18.104.22.168 which is the routing engine. I also have a transform that changed degree C to degree F
The Alert watches for row 22.214.171.124 to exceed 120 degrees F and Emails and sets an Event in the event log.