R&S XU 4200  Main/Standby Operation (1:1) 
6166.5368.02.01 3.78   
3.6.4  Limitations/Notes 
 
Please note that there are certain limitations for the main/standby operation:
  Main and Standby radio configuration with NoGo state on radios wired 
as 1:1 M/S pair must be avoided 
 
In case of the NoGo state on both radios, both TEST_OC lines become 
open (both radios are reporting a request for M/S switchover). This 
state brings the radios to ACTIVE state when they can receive and 
transmit simultaneously. This can be dangerous especially for 
transmitters. 
 
Example of an incorrect radio configuration:  
 
– HW Configuration: Main and Standby radios are supplied from the 
same mains. Both radios are connected to a DC backup battery 
– CBIT Configuration: AC-Main Supervision is configured as "NoGo" on 
both Main and Stadby radios. If the AC main fails, the radios will 
request the M/S switchover and switch to the unwanted ACTIVE state 
 
Note: If one radio is in local mode while the other one is in remote mode, 
then the locally operated radio is active and the second one is inactive. This 
setting remains even when the local mode is left. The main/standby 
switchover capability of the radio pair is now available. 
Note: The “Inactive Warning” parameter should be set to “Disable” to avoid 
the inactive "Standby" radio showing the CBIT event “INACTIVE 
WARNING”. 
Note: Set the “Line Interface in Local Mode” parameter to “Disable”. 
Note: Make sure that all operational parameters are equal on both radios 
(with exception of IP address).