Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546
(OP) 5-109
OP
The switch labeled ‘Clockswitch’ is provided to invert the V.35 transmit timing clock signal if
required.
The switch labeled ‘Fiber-optic Loopback’ is provided to allow a test loopback of the
communication signal across the fiber optic terminals. When switched on, the red LED
labeled 'Fiber-optic Loopback' is illuminated.
The switch labeled ‘V.35 Loopback’ is provided to allow a test loopback of the
communication signal across the X.21 terminals. It loops the incoming V.35 ‘Rx’ data lines
internally back to the outgoing V.35 ‘Tx’ data lines. When switched on, the red LED labeled
‘V.35 Loopback’ is illuminated.
The switch labeled ‘DSR’ is provided to select/ignore the DSR (Data Set Ready)
handshaking control signal. The red LED labeled DSR Off is extinguished either when DSR
is asserted or when overridden by setting the DSR switch On.
The switch labeled ‘CTS’ is provided to select/ignore the CTS (Clear To Send) handshaking
control signal. The red LED labeled CTS Off is extinguished either when CTS is asserted or
when overridden by setting the CTS switch On.
The switch labeled ‘Data Rate’ is provided to allow the selection of 56 or 64k bits/s data rate,
as required by the PCM multiplexing equipment.
The LED labeled ‘Supply Healthy’ is green and provides indication that the unit is correctly
powered.
Please refer to Installation chapter for the external connection diagram.
The P54x may be set either with Clock Source as ‘External’ for a multiplexer network which
is supplying a master clock signal, or with Clock Source as ‘Internal’ for a multiplexer
network recovering signal timing from the equipment. Refer to Section 2.3.3.
2.1.11
Multiplexer link with X.21 electrical interface usi
ng auxiliary optical fibers and type P593
interface
The P593 unit supports the ITU-T Recommendation X.21 interface. It is approved as line
interface equipment by the British Approvals Board for Telecommunications (BABT) for
connection to the services described in this section; License Certificate Number
NS/1423/1/T/605362.
A P54x relay with 850 nm short haul optical interface is connected to a P593 unit by 850 nm
multi-mode optical fiber. Multi-mode fiber type 50/125 m or 62.5/125 m is suitable.
BFOC/2.5 type fiber optic connectors are used. The P593 unit converts the data between
optical fiber and ITU-T compatible X.21 electrical interface. The X.21 output must be
connected to an ITU-T compatible X.21 channel on the multiplexer or ISDN digital data
transmission link.
P593
P540
850nm
P540
850nm
O/FO/F
P593
X.21
The P54x relays require a permanently open communications channel. Consequently, no
communications handshaking is required, and it is not supported in the P593 unit. The
signals supported are shown in the following Table.
ITU-T Recommendation X.21 is closely associated with EIA specifications RS422 and
RS449. The P593 can be used with RS422 or RS449 communications channels which
require only the signals shown overleaf.
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