July 2013 © British Telecommunications plc 2013
Page 5
Figure 4 - Utilising the Pos bus rail
Outputs
Three transistor outputs are provided on screw terminals at the top of the unit, and these have
an associated 0V terminal on the 4
th
connector on the block. The outputs are transistor driven
and use an internal 10K resistor to give the high state.
By default, output 1 is comms Fail, output 2 is CTRL, and output 3 is RPS. See the further
sections on outputs for a full explanation.
Serial data connections
RS232 TX & RX is also provided and RS485 A & B on another 4 way terminal block.
These ports allow serial alarm panel connection. See Panel Upload Download section.
PSTN connection
The telephone line connection is made to a 2 way terminal block at the top right of the unit.
The PSTN connection is not polarity sensitive. Connect the terminals to a standard PSTN line
that supports DTMF outgoing access.