EXFO IQS-600 Integrated Qualification System - Manual (Page 45)

Getting Started with Your Integrated Qualification System
Integrated Qualification System 37
Safeguarding Units with the Interlock
If you use modules featuring an interlock, these terminals must
communicate, whether it is directly or via the external security device.
Otherwise, your modules will not function properly.
The output voltage is 5 V. Do not apply any voltage to the interlock
terminals, since only a mechanical contact is needed.
For more information about the type of interlock system to use with the
module you are working with, refer to the corresponding user guide.
C
AUTION
The Interlock ground is NOT intended to ground the whole unit. It is
used for the interlock cable shielding connection only.
I
MPORTANT
Some modules have an interlock located on the front panel. Use the
front interlock instead of the one located at the back of your
controller unit, as the latter will not offer you any protection.