Can the software contact the Logger?
When the software talks to a Logger module, the module's busy light comes on. It remains on until the software talks to another Logger. The busy light is on the back panel of a boxed Logger, and on the Logger module's front panel in a rack-based system. If you only have one Logger then the light will remain permanently on.
The busy light is useful for diagnosing problems. If you remove the power supply from the unit and then reconnect it, the busy light will be off. If it goes on when you talk to the unit then you can see to which one you are talking and confirm that the software has found it.
Next: Finding Missing Units.