Figure 9. Multiple Lobby Control Units To Multiple Lines - Mircom TX3 Series Installation And Operation Manual

When Lobby Control Unit 1 is using line 1 and Lobby Control Unit 2 also wants
to use line1, which is busy, then a line busy message displays on Lobby Control
Unit 2.
Lobby
control
unit 1
RS-485 from
previous unit
Figure 9.
Version 1.6 Telephone Access System Installation and Operation Manual
LT-969 Copyright 2012
Lobby
control
unit 2
Line3
Line2
Line1
1 2 3 1 2 3
4 5 6 4 5 6
7 8 9 7 8 9
* 0 # i * 0 # i
RS-485
bus
Multiple Lobby Control Units to Multiple Lines
NSL
Control
Unit
Lobby
control T/R
unit 3
1 2 3
4 5 6
7 8 9
* 0 # i
RS-485 to
next unit
TX3 System
NSL
Control
Unit
T/R
T/R
Telephone outlet
Central office line
33 (112)