This KB explains the behavior of how jnxFru-related MIB information is displayed on Junos and Junos Evolved platforms.

When a FRU(Field-replaceable unit) is removed from the system and the slot is empty, Junos devices display a value of 2, indicating an empty state, as shown in the MIB information below.

In contrast, on Junos Evolved devices, the OID corresponding to an empty slot is not displayed at all.
Both behaviors are expected and are by design.

----------------------------
jnxFruState
1.3.6.1.4.1.2636.3.1.15.1.8

INTEGER
unknown(1)
empty(2)
present(3)
ready(4)
announceOnline(5)
online(6)
anounceOffline(7)
offline(8)
diagnostic(9)
standby(10)
----------------------------