ABB AC 900F Mounting And Installation Instructions Manual page 32

LED display and control elements
Both controllers perform the command (Run or Stop). The LED display on the
Primary shows the current status. In the case of a redundancy change-over, the last
status is retained irrespective of the RUN/STOP switch position.
Change-over to Run
Change-over to Stop
TOGGLE switch
With a redundant AC 900 F configuration in synchronized state, a change-over of
the TOGGLE switch on the Primary produces the following effect: The previous
Secondary changes immediately to Primary and the previous Primary to Secondary
without requiring any system rebooting. Any actuation of the TOGGLE switch on
the Secondary will be ignored.
RESET switch
The RESET switch is used to reset the AC 900F. Depending on the system status,
either a warm or a cold start is initiated. A "tool" (e.g. a ball pen or similar) is
required to actuate the RESET switch.
When the RESET switch is pressed for a specified time, the following functions will
be released:
Single controller
< 4 s = Warm start
> 4 s = Cold start
Redundant controller
< 4 s = no function
> 4 s = redundancy change-over and cold start of the controller with actuated
RESET switch
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Normal operation. The program sequence is started. If the module is
reset and a self-test is subsequently started, no configuration menu
appears at the diagnostic interface.
The program sequence is stopped. If the module is reset and a self-
test is subsequently started, the configuration menu appears at the
diagnostic interface.
Section 3 Modules
M&I – AC 900F Controller