Siemens SINAUT ST7 System Manual page 228

Installing and putting a SINAUT modem into operation
5.7 Analog dial-up modem MD3
The RTS and CTS signal names are irrelevant for the MD3.
The following table summarizes the meaning and activity of the six LEDs on the front of the
modem for dedicated line operation.
Table 5- 23
LED no.
1
2
3
4
5
6
The RTS, CTS and RI signal names are irrelevant for the MD3.
228
Meaning of the LEDs on the front of the MD3 for dedicated line 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.
DTR Data terminal ready
This LED indicates the signal state of the DTR line of the data terminal
equipment (TIM). Due to the default setting of the MD3, the signal state
of the DTR line in the dedicated line mode has no effect on the modem.
RTS / ONL Modem online (ONL)
The modem attempts to establish a connection to the partner modem
after power ON; in other words, the two modems attempt to
synchronize themselves. As soon as they are synchronized, the ONL
LED remains lit but the DCD LED goes off.
If there is no synchronization within 60 seconds, the ONL LED goes off
briefly and then lights up again to indicate that the modem is attempting
to synchronize once again.
CTS / RI -
DCD The LED has a dual function:
1. Operating status
This signals the operating status of the modem. The LED lights up after
the power is turned on if the operating voltage is correct. If the modem
is not operational, the LED remains off.
2. Connection established
The LED goes off as soon as the two modems involved in connection
establishment are synchronized (see also "ONL" LED). The LED lights
up when the connection was aborted due to a disruption.
System Manual, 07/2009, C79000-G8976-C178-07
Station control system