Emerson ControlWave Instruction Manual page 66

ControlWave I/O Expansion Rack Instruction Manual
Software Configuration To use data from any ControlWave DO module in the rack you must
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use ControlWave Designer's I/O Configurator to modify the
ControlWave project in the host controller to add an ER_DO32 board
and then configure it. See the ControlWave Designer Programmer's
Handbook (D5125) for more information. That same manual includes
an I/O Mapping section that describes, for advanced users, the I/O map
for this module.
DO with Readback in a Redundant System
Variables in the ControlWave project govern how inconsistencies
between the online DO module and the standby DO module are
handled in redundant systems with DO readback. Information on
configuring system variables is included in the ControlWave Designer
Programmer's Handbook (D5125).
If there is a discrepancy between the value of the online and standby
DOs, the system sets a status variable mapped by the _ER_STAT
virtual status board to TRUE. By default, the name of the variable
follows one of two possible formats.
ERSTAT_n_RDN_IO_x_ERR
ERST_n_RDN_IO_x_ERR
where n is the I/O slot number of the virtual ER_STAT board, and x is
the I/O slot number of the digital output module that has a failure. See
the I/O Configurator and I/O Mapping sections of the ControlWave
Designer Programmer's Handbook (D5125) for more information. You
can optionally rename these variables.
You should configure these variables as alarms so you receive
notification of a failure of the backup DO module. See the
ControlWave Designer online help for information on alarm
configuration.
When a read-back failure occurs, the FAIL LED remains RED until the
unit reboots, either through a sideload, forced redundant switchover, or
power-down and restart, or you remove and replace the board (hot card
replacement). Each of these operations momentarily turns the FAIL
LED to GREEN (and the associated _ERR error variable to FALSE)
until a new readback failure occurs, which changes the LED back to
RED, and the associated _ERR error variable back to TRUE.
Another variable which you must map from the _ER_STAT virtual
status board determines whether a failure of the standby DO (as
indicated by the LED and associated _ERR error variable) should only
be treated as a warning condition, which would still allow a failover to
occur, or as an error which would prevent a failover to the standby. By
default, this variable is named either ERSTAT_RDN_IOERR_WARN
(or ERST_RDN_IOERR_WARN). You can change the default names
as needed.
When you set this variable to FALSE, the system treats a DO readback
I/O Modules Revised Aug-2015