17
© MiMOMax 2013 Four Wire Audio
Interface Manual
Three modes of operation are supported.
7 channel mode where up to 6 audio channels and a single data channel are available.
3 channel mode where 2 audio channels and a single data channel are available.
Fixed channel mode where 2 audio channels only are available.
The 3 and 7 channel modes provide for static (always up) or dynamic (E&M controlled)
operation while fixed mode provides only for always up operation.
4.3
E
&
M
S
IGNALLING
For all dynamic audio channels an E-Lead signal is required for audio to pass through the
system.
For ‘Static’ audio channels an E-Lead signal is NOT required and may be left unconnected.
The M-Lead signal will always reflect the current output audio status of the port independent
of the selected configuration.
A basic E&M signalling interface is provided utilising an opto-isolated switch for the output
(M-Lead) and an opto-isolated current sense input (E-Lead).
The M-Lead will present an on resistance of < 40ohms when active and can support a load
current of up to 100mA over the voltage range of 10V to 50V. The interface is polarity
insensitive.
The E-Lead will detect a current of 5mA or greater as active. Internal current limiting is
provided with a supported voltage range of 10V to 50V. The interface is polarity insensitive.
M Lead
sense (including voltage source)
Pin 7
Pin 8
Internal signal
Four Wire Audio Unit
Customer Equipment
The FWA unit internally provides a switch across the M-Lead pins. The external sense
circuit is required to provide its own voltage source which will allow a switch open or closed
state to be sensed.
E Lead
10 to 50 volts DC
Pin 1
Pin 2
sense
Internal signal
sense
Customer Equipment
Four Wire Audio Unit
The FWA unit internally senses a DC voltage across the E-Lead pins. A DC voltage
between 10v and 50v will allow the audio presented to the associated audio port to pass to
the other end.
