National Instruments FP-3000 - Manual (Page 73)

Chapter 4 Block Reference
© National Instruments Corporation 4-21 FieldPoint FP-3000 User Manual
Status refers to the quality of a variable communicated between two blocks.
When a block receives a variable with bad status, it can affect its current
mode of operation.
Status Handling
Parameters that can be communicated between blocks are composed of a
value and a status. The value is the data to be communicated, and the status
describes the quality of the data. When two blocks are logically connected
over the Fieldbus using host configuration software, the block that is
sending data is called the publisher. The block receiving the data is called
the subscriber. When communication is established from a publisher to a
subscriber, the subscriber takes the value and the status of the published
variable. If communication is not established between the publisher and the
subscriber, the subscriber has a status that reflects the lack of
communication. Statuses themselves are composed of three subfields: the
quality, the substatus, and the limit.
Quality
Table 4-7 describes the Quality subfields.
Table 4-7. Quality Values
Value Meaning
Bad The value is bad, the sensor is defective, or
communication has not been established. The
value should not be trusted by the receiver.
Uncertain The quality of the data is unknown. This can be
caused by errors or a lack of calibration in the
physical I/O transducer. Blocks can generally be
configured to treat values of
Uncertain quality
as either Bad or Good with the STATUS_OPTS
parameter.
Good_NonCascade The value is good and from a block that does not
support cascade initialization. This status is also
used when an alarm is active.
Good_Cascade The value is good and from a block that supports
cascade initialization.