YSI IQ SensorNet 2020 XT Terminal - Manual (Page 120)

Operation System 2020 XT USB
4 - 42 ba76019e01 12/2012
Event:
Failure of the main
controller
(MIQ/TC 2020 XT
controller operation)
 If the MIQ/TC 2020 XT (configured as a terminal) receives no more
valid telegrams from the main controller for a period of 2 min, it
takes over the controller operation as a backup controller. The MIQ/
TC 2020 XT is reinitialized.
 On takeover of the controller operation a logbook message is
generated.
 In the MIQ/TC 2020 XT backup controller operation
– the status LED flashes
– BACKUP CONTROLLER appears on the display alternately with
the terminal name
– the MIQ/TC 2020 XT (configured as a terminal) keeps its own
logbook. The logbook is empty when the controller operation is
adopted. The topmost message contains the reference to
controller operation. It can neither be acknowledged nor deleted.
The logbook is deleted when the controller operation is
terminated.
Event: Main controller
goes back into operation
 As soon as the MIQ/TC 2020 XT (configured as terminal) again
receives a valid telegram from a main controller in the
IQ S
ENSOR N ET , it is reinitialized as a regular terminal. The main
controller works again as a regular controller. It uses its own settings
for this (or the factory settings in the case of a brand new controller).
 The MIQ/TC 2020 XT (configured as terminal) detects whether the
system configuration in the main controller differs from the backed-
up system configuration and, if necessary, offers to restore the
backed-up system configuration on the main controller.
If the system configuration is not restored onto the main controller,
the first regular backup from the main controller to the MIQ/
TC 2020 XT is immediately carried out.