Siemens SIMATIC NET TeleControl SINAUT ST7, Системное руководство

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Installation and commissioning of the modems and routers
5.8 ISDN dial-up modem MD4
SINAUT ST7 station control system
System Manual, 09/2016, C79000-G8976-C178-10
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LED no. Labeling Description
3 DTR End devicel ready
Outgoing call:
The LED lights up when the end device (TIM) wants to establish a con-
nection and goes off as soon as the end device wants to terminate the
established connection. If no connection can be established or the con-
nection is terminated by the partner or is aborted due to a disruption, the
end 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 end device (TIM) wants to accept an incom-
ing call. The LED goes off again under the same conditions as with an
outgoing call.
4 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 end device (TIM) and begins connection establishment. The
LED goes off again when the connection is terminated (by its own end
device or by the partner) or when the connection is aborted due to a
disruption.
Incoming call:
The LED lights up when the end 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.
5 CTS / RI Ring indicator (RI)
The LED is lit with each ring of an incoming call.
6 DCD Connection established
The LED goes on, as soon as the two modems involved in the connec-
tion establishment are synchronized (indicated on the end device (TIM)
by CONNECT). The LED goes off when the connection is terminated or
aborted due to a disruption.
The RTS and CTS signal names are irrelevant for the MD4.