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Chapter 5
Backing up the DPU
Overview
In a redundant configuration, two DPUs are connected to form a backup pair.
One DPU is designated as the primary unit and the other DPU the secondary
unit. The DPU Bus station address of the secondary station is one number
greater than the address of the primary station.
The installation, preparation, and adjustment procedures included in this
publication apply to both DPUs in a redundant configuration. This chapter
provides information on switches and cabling in a redundant configuration.
Automatic Failover/Manual Takeover
Process control can be transferred automatically (Failover), or you can
manually command takeover. Automatic Failover can only occur from the
primary DPU to the secondary DPU; a secondary DPU will never auto-
matically failover to a primary unless the secondary loses power or is reset.
Automatic Failover
Process control is automatically transferred from the primary DPU to the
secondary DPU when the primary DPU experiences a severe diagnostic
alarm or when communication between primary and secondary DPU is lost.
However, if the secondary DPU is itself experiencing a severe diagnostic
alarm, it will refuse control, unless the primary DPU loses power or is reset.
After the alarm condition in the primary DPU is rectified, acknowledge all
remote alarms, confirm configuration using Interaction Page 9, and press the
takeover button on the front panel of the primary DPU to return control.
Manual Takeover
To manually command either DPU to assume control, press the takeover
button on the front panel of the unit. Manual takeover will occur even if a
severe diagnostic alarm or a fatal alarm condition exists in the DPU whose
button is pressed.
Metso Automation MAX Controls • • • • 277573 • • • •
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