10
6
F
2
S
0
7
5
5
3.3 Indications
The G1IF1 unit provides four light emitting diodes (LEDs) for indication purposes. Table 3.2
details the labels, colours and functions associated with each LED.
Table 3.2 Indication LEDs
LED Label
Colour
Function
Power
Green
Lit when auxiliary dc power is present
TX from COM
Yellow
Indicates data transmission from the telecommunications channel to the
GRL100 relay
TX from RELAY
Yellow
Indicates data transmission from the GRL100 relay to the
telecommunications channel
CLK from COM
Yellow
Indicates the timing signal from the G703 or X.21 interface.
3.4 Response during Communication Fail
(1) When the data transmission from telecommunication multiplexer to G1IF1 is stopped:
The LED “TX from COM” turns off and the data “0” is transmitted to the relay. At that time,
the relay at local terminal detects a communication failure.
(2)
When the data transmission on fibre optic interface from the relay to G1IF1 is stopped:
The LED “TX from RELAY” turns off and the send signal (the voltage between terminals
TB1-6 and TB1-7) becomes “0V”. “0V” means undefined data in G703-1.2.1 and means “0”
data in G703-1.2.2 / 1.2.3.
(3) When the timing signal
from telecommunication multiplexer to G1IF1 is stopped:
The LED “CLK from COM” turns off and the data transmission on fibre optic interface from
G1IF1 to the relay is stopped.
The data transmission to telecommunication multiplexer is
continued. The relay at the remote terminal detects a communication failure intermittently
because the bit synchronising between the relay at the local terminal and telecommunication
multiplexer.