BFM 400 Microphones
Operating Instructions
BFM400 Operation Manual issue 7
9
2.5 E
LECTRICAL
C
ONNECTIONS
All electrical connections to the microphone are made using the
connector block mounted on the termination PCB.
To avoid the possibility of interference between the Audio and
Data we recommend each microphone is connected using two
separate 4 core Fire Rated cables, one carrying the Audio pair and
the other the Serial Data pair.
Figure 2.5 — Termination PCB
N
OTE
: The Termination details shown on the PCB are for Serial
Connection using RS485 data.
Refer to the table below for Parallel Connection details.
The BFM Factory Default setting is "Serial".
Legend
Serial Connections
Parallel Connections
RS485A
RS485 Transmit
"PTT" (Closes to 0V when PTT is pressed)
RS485B
RS485 Receive
"Busy" (Close to 0V to illuminate Busy LED)
GND
Ground
Ground
+V Supply
+24V Input
+24V Input
0V Supply
0V
0V
GND
Ground
Ground
Audio
Audio Line
Audio Line
Audio
Audio Line
Audio Line
Bypass
Bypass "All Call" Access Bypass "All Call" Access
GND
Ground
Ground
