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Overview of Quantum Hot Standby
20
840 USE 106 00 January 2003
Function
Keyswitch
Beneath the LED display on the face of each CHS 110 control panel is a function
keyswitch. It has three positions: Off Line, Xfer (transfer) and Run. You may use this
switch to force transfer of control functions or to copy the full program from the
Primary controller to the Standby.
The following illustration shows a function keyswitch with three positions: Off LIne,
Xfer and Run.
Designation
Slide Switch and
Update Button
A slide switch located below and to the right of the keyswitch is used to designate
the controller as A or B. One unit must be designated as A and the other as B.
Use the Standby Update Button to initiate the Primary to Standby program transfer.
You must have the keyswitch in transfer mode.
Note: For security or convenience, you can disable the function keyswitch with a
software override. Once the keyswitch is disabled, you can set the module to run
or offline mode with software. This can be especially helpful when the module is
not easily accessible.
Off
Line
Xfer
Run
Note: If the controllers are given identical designations, the system refuses to
acknowledge them both. The first unit to power up will be recognized as the
Primary controller. It is designated A or B according to its switch position. The
second unit remains offline and the ComAct indicator flashes, indicating a startup
error.
Note: Once the system is running, Primary control may be exchanged between the
units regardless of which is designated as A or B.