On the MX80 (including MX5, MX10, MX40) platform, an unpowered PEM is not detected, which is expected behavior.

When both (PEM 0 and PEM 1) are powered on, the states have the following values:

When PEM1 is unplugged from a power source, the following is returned:

On other MX platforms like MX480, the output is:

lab@MX480> show snmp mib walk jnxOperatingState.2.1
jnxOperatingState.2.1.0.0 = 6


From the MIB, 2 and 6 represent:

running(2), -- up and running,
down(6), -- down or off, for power supply


Other platforms use a control board to provide this functionality.

This is expected behavior, as the platform lacks the capacity to detect a PEM as inserted when there is no power to it.