11.8.11 RSC Switch Card
Theory of operation
The RSC- Redundant Switch Control card controls the
switchover of the reference clock in redundant systems
with two receiver units. The RSC is used to switchover
the pulse and frequency outputs and the serial inter-
faces between the available receivers. The controls of
the module allow the selection of different modes in
which the RSC operates. The status LEDs indicate
which receiver is selected as a master clock and the
current operating state of the switching module.
Switch Position "Auto/Manual"
This switch selects between automatic and manual
mode. In the manual mode the module’s internal se-
lection logic is overridden and the current system for
signal generation can only be selected manually by the
switch Clock 1 /Clock 2. In the manual mode outputs
are always enabled, regardless of the synchronization
state of the clocks.
Switch Position "Auto"
The selection of the reference is done by an internal switch-logic of the RSC. The selection of the active system
based on the TIME_SYNC signals which are generated by the receivers. The TIME_SYNC signals are indicate
the synchronization of the clocks.
To avoid unnecessary changeovers in case of repeatedly occurring free run operations of one system, the
master/backup order is changed with each changeover. For example, let’s suppose the current master system
looses its synchronization. Then a changeover is performed to a synchronous slave system and thus the former
slave system becomes a new Master. No changeover is done if both systems are asynchronous. In this case the
current state stays the same.
Important:
To ensure an automatic switchover the Manual function should be disabled via display-menu. "Ref.
Time
→
Switch Unit":
Select Switch Unit
→
SCU Cntl
→
MANUAL: disable
. Otherwise, the system depends
on the clock selected by the manual control function and the unit will not switch over to the current active clock.
Manual Mode (Display Menu)
In this operation mode the selection of the reference clock is done by a display menu. A switchover of the
reference clock in case of an error does not happen, pulse and frequency outputs and the serial interfaces are
always enabled.
Display Menu:
Switch Unit
→
SCU Cntl
→
MANUAL : enable
Note:
For systems without display (M1000S, M2000S and M3000S) a LANTIME Display Unit (LDU) can optionally
be used.
80
Date: 27th May 2021
IMS - LANTIME M4000
