Rockwell Automation 1757-FFLDC4 FOUNDATION Fieldbus System User Manual - Manual (Page 107)

Rockwell Automation Publication 1757-UM012A-EN-P - July 2011 107
Linking Device Function Blocks Chapter 7
Nonvolatile Parameters
The linking device has a mechanism to save nonvolatile parameters into
nonvolatile memory during the power down sequence. Parameters are recovered
during the power-up sequence.
Alert Notification
The MAX_NOTIFY parameter value is the maximum number of alert reports
that this resource block can send without getting a confirmation, corresponding
to the amount of buffer space available for alert messages. The
CONFIRM_TIME parameter is the time that the resource block waits for 1/32
of a millisecond for confirmation of receipt of a report before trying again. If the
CONFIRM_TIME is zero, the device does not retry.
FEATURES / FEATURE_SEL Parameters
The bit strings FEATURES and FEATURE_SEL determine optional behavior
of the resource block. The first defines the available features, and is read only. The
second is used to turn on available features. If a bit is set in FEATURE_SEL that
is not set in FEATURES, the result will be a block alarm for a configuration error.
The linking device supports the following features: Reports, Fault State, Soft
Write Lock, and change of Bypass in Auto Mode.
Fault State
If you set the SET_FSTATE parameter, the FAULT_STATE parameter indicates
active and causes all output function blocks in the resource block to go
immediately to the condition chosen by the fault state Type IO_OPTS selection.
Clear it by setting the CLR_FSTATE parameter. The set and clear parameter
values do not appear when viewing through online characterization because they
are momentary.
Write Lock
The WRITE_LOCK parameter prevents any external change to the static or
nonvolatile data base in the function block application of the linking device.
Block connections and calculation results proceed normally, but the
configuration is locked. You set it and clear it by writing to the WRITE_LOCK
parameter. Clearing WRITE_LOCK generates the discrete alert WRITE_ALM,
at the WRITE_PRI priority. Setting WRITE_LOCK clears the alert, if it exists.
Before setting WRITE_LOCK parameter to locked, you must select the “Soft
Write lock supported” option in FEATURE_SEL.