Guralp Systems CMG-3T - Manual (Page 38)

CMG-3T
The five-stage process comprises locking the Z, N/S and E/W masses,
followed by longer periods tilting the N/S and E/W sensor base to their
end stops. During the latter two periods, the position of the N/S and E/
W masses will “flip” to one side.
The BUSY LED is lit during each stage, but goes out briefly between
stages, allowing you to follow the progress of the lock.
UNLOCK
This command unlocks the sensor masses and prepares the instrument
to begin operating.
If UNLOCK is activated when the masses are already unlocked, the
processor will lock them and attempt to unlock again. This is useful if
you suspect that the locking procedure has failed.
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