metso automation PDP 400 maxDPU4F Series, Руководство по оборудованию

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Chapter 6
Redundant DPU Operation
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 IP address of the secondary DPU is always one number greater than
the address of the primary DPU. The primary is always the even address
while the Secondary is the odd address.
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 can be
manually commanded to takeover. Automatic Failover can occur from either
the primary DPU to the secondary DPU or from the secondary to primary
based on the health of each DPU.
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.
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 only if the
inactive DPU is healthy enough to assume control. If a severe diagnostic
alarm or a fatal alarm condition exists in the inactive DPU then the Take
button will be ignored. For a more complete discussion of manual takeover,
see Chapter 3, “Using the Takeover Button.”