ABB AC 900F Mounting And Installation Instructions Manual page 20

Controller redundancy
If the primary controller (Primary) fails, the secondary controller is activated via a
designated communication connection (redundancy link).
The cyclical adjustment ensures smooth change over from the primary to the
secondary controller, i.e.
•
•
•
AC 900F in redundant configuration using the on-board interfaces for Modbus and
telecontrol protocols.
Controller Redundancy us.png
20
the outputs of fieldbus-connected I/O components are maintained.
the internal status (component data, variables) is maintained.
the configuration and operating data of the primary and secondary controllers
are automatically adapted.
Section 2 Configuration
M&I – AC 900F Controller