5
X
RS-232,485 + 2
X
E
THERNET
/2 M
BIT
/
S
G.703 (G.704) M
ULTIPLEXER
O
PERATING
M
ANUAL
IOA81-1E
17
August 2004
3.9 Operation with the TM-48 device
The TM-81 multiplexer can operate with the TM-48 device, when transmission of data is
effected through tributary RS-232 ports. Asynchronous RS-232 ports in the TM-81 device can
be switched to operation with the TM-48 device. After such switching the principle of insert-
ing of asynchronous data stream appearing on the RS-232 port into the 64 kbit/s slot of the
G.704 stream changes and becomes same as in the TM-48 device. Changing the operating
mode of RS-232 ports require reconfiguration of the multiplexer in the way described in point
5.1.
Switching over into the operating mode with the TM-48 device causes that RS-232
channels work at the speed of 50 – 9600 bit/s. In this mode neither configuration of the speed
nor setting the start-stop frame format is necessary. When the device works as compatible
with the TM-48 device, the co-operation with the RS-232 interface only is possible. The RS-
485 interface can’t be used.
Regardless the operating mode configured on the RS-232 ports, the way in which the
devices on 2048 Mbit/s line ports are connected remains unchanged. Both point-to-point and
bus configuration are permitted. Also, the principles of configuring the clock in such connec-
tions remain the same as for connections effected by using the TM-81 devices only.
3.10 Operation as a terminal equipment
If there is no 2048 kBit/s signal connected to one of line ports (A or B), the multiplexer
should work as a terminal device. Then the device works with the own 2048 kbit/s clock or
with the clock reproduced from the G.703 interface and generates the frame compliant with
the ITU-T G.704 recommendation towards the used port.
The TM-81.1 device is able to automatically switch itself into the terminal device operat-
ing mode, or may be toggled into this mode by using a switch.
If the device is not configured as the terminal device, then it switches automatically into
the terminal device operating mode when the loss of 2048 kbit/s signal is detected or when it
receives an AIS signal (111111... sequence). At the same time, the alarm bit in the TS0 slot
not containing synchronization pattern towards the used port is set. When the signal appears
again or AIS signal diminishes, the device resumes operation with two ports.
If the multiplexer is configured as a terminal device by using a switch, then in the case of
loss of 2048 kbit/s signal or detection of the AIS signal from the direction of unused port the
alarm bit in TS0 slot is not set.
The multiplexer can be set as the terminal device by using CONFIGURATION switches
(see point 5.5 –
Selection of operating mode)
.
3.11 Establishing the clock source
Selection of clock source is possible only when the multiplexer is set to operation as a
terminal device by using a switch.
Automatic setting into terminal device operating mode always causes the use of clock
from internal generator.
Summary of Contents for TM-81.1
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