18
6 Optical Signalling at NT1+2a/b
The equipment has 2 LED to display various operating states. The states marked in
bold letters denote the display state in normal mode.
LED ~ (yellow) ON
local main power supply (230 V ~)
OFF
remote power (no local power supply)
LED U (green) ON
U interface is activated, an ISDN device is
connected at S/T interface, Layer 1 is activated
Flash slow (1 Hz) U interface is activated, no ISDN device is
connected at S/T interface; Layer 1 is activated
via the analogue ports
Flash fast (8 Hz)
U interface in synchronisation state,
permanently in error case at U interface
OFF
Layer 1 is deactivated (in “sleep” mode)
7 Connection configuration
Analogue Telephone 2
Analogue Telephone 1
S/T
ab/2
ab/1
max. 6 x ISDN Terminal
Equipment
230V~
U-interface
Figure 2
