Siemens SINAUT ST7 System Manual page 259

LED displays of the MD4
The following table summarizes the meaning and activity of the six LEDs on the front of the
modem for dial-up operation.
Table 5- 41
LED no.
1
2
3
4
5
6
The RTS and CTS signal names are irrelevant for the MD4.
Station control system
System Manual, 07/2009, C79000-G8976-C178-07
Meaning of the LEDs on the front of the MD4 for dial-up operation
Labeling Description
TXD Transmit data
The LED flashes in rhythm with the data flow sent to the modem by the
terminal device (TIM) over the RS-232 or RS-485 interface.
RXD Receive data
The LED flashes in rhythm with the data flow sent by the modem to the
terminal device (TIM) over the RS-232 or RS-485 interface. The data flow
is indicated both in the data and in the command phase.
DTR Data terminal ready
Outgoing call:
The LED lights up when the terminal device (TIM) wants to establish a
connection and goes off as soon as the terminal device wants to
terminate the established connection. If no connection can be
established or the connection is terminated by the partner or is aborted
due to a disruption, the terminal device deactivates the DTR signal as
soon as it receives a message to this effect from the modem.
Incoming call:
The LED lights up when the terminal device (TIM) wants to accept an
incoming call. The LED goes off again under the same conditions as with
an outgoing call.
RTS / ONL Modem online (ONL) "receiver taken off the hook"
Outgoing call:
The LED lights up as soon as the modem has received the dialing string
from the terminal device (TIM) and begins connection establishment. The
LED goes off again when the connection is terminated (by its own
terminal device or by the partner) or when the connection is aborted due
to a disruption.
Incoming call:
The LED lights up when the terminal device (TIM) signals with DTR that it
wants to accept the incoming call. The LED goes off again under the
same conditions as with an outgoing call.
CTS / RI Ring indicator (RI)
The LED light ups with every ring of an incoming call.
DCD Connection established
The LED lights up as soon as the participating modems are synchronized
during connection establishment (signaled to terminal device (TIM) with
CONNECT). The LED goes off when the connection is terminated or
aborted due to a disruption.
Installing and putting a SINAUT modem into operation
5.8 ISDN dial-up modem MD4
259