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Using a Quantum 984 HSBY System
94
840 USE 106 00 January 2003
Transfer All State RAM
"Transfer All
State RAM"
check box
It is not possible to define a special State RAM or additional State RAM range to be
transferred if this check box is activated.
Nontransfer Area The nontransfer area contains the Hot Standby status register, which is used to
monitor the states of both controllers. It also contains a pair of registers which may
be used for reverse transfer operations. You may include other 4x registers in the
nontransfer area to reduce scan time.
The Start: field is used to specify the first 4x register in the nontransfer area. The
Length: field is used to define the number of contiguous registers in the nontransfer
block. If you choose to define a nontransfer area, the range of legal values for this
entry field is 4 ... n, where n is the number of configured 4x registers. However, when
defining the nontransfer area, you must meet these requirements:
The nontransfer area must be located entirely within the area of 4x registers
scheduled for transfer on every scan. The transfer area is defined in the State
RAM dialog.
The command register (first entry of the Hot Standby dialog) must be outside the
nontransfer area.
Hot Standby
Status Register
The third register in the nontransfer area is the Hot Standby status register. Use
this register to monitor the current machine status of the Primary and Standby
controllers.
Note: If you are also programming a CHS instruction in LL984, the parameters you
set for the nontransfer area in the Hot Standby dialog must be identical to those in
the CHS block.