Capt Kremin:
I agree, however the aircraft I fly has the same switch and it doesn't cut off the Cabin SATCOM link.
What type of aircraft is that; B777, or something else?
That does not mean that the SATCOM call capability from the Cabin Managers station was disabled. Qantas use a similar system and have the ability to make a SATCOM call from the CSM's station even though the seat capability is similarly disabled, even with the IFE switched off.
Again, which aircraft type?
It would be very interesting to find out more about the CPMU to ascertain if it is de-powered by the IFE switch.
I can see good reasons why it would not be, particularly if it also controls cabin lighting, cabin comms and PA functions.
The CPMU is part of the Cabin Passenger Management System (CPMS) that is used to manage cabin-related data such as audio/video program libraries, passenger lists, destination information, cabin crew flight reports, connecting flight information, flight arrival information, 'Airshow' information, etc. The CPMU is the main controller that transmits data to other CPMS components and also acts as an interface to other aircraft systems. Based on the description of the CPMU in the FI, it provides an interface between the IFE system and the SDU for SMS and e-mail messages.
The CPMU does
not control functions such as cabin lighting, cabin interphone, PA, etc, which are all controlled by the Cabin Services System.
The Boeing Service Bulletin that MickG referred to in an earlier post required the engineers to check that power was available to the CPMU with the IFE/PASS SEAT switch selected ON. There was no associated check with the switch selected OFF, but it seems that the switch position might affect the supply of power to the CPMU.