Advanced Features - Emerson Rosemount 3144P Reference Manual

Reference Manual
00809-0100-4021, Rev JA
4.9.5 Status
When a PV is passed from one function block to another, it passes a STATUS along with the PV. The
STATUS can be: GOOD, BAD, or UNCERTAIN. When a fault occurs in the device, the PV will look at the last
value with a STATUS of GOOD and the STATUS will change from GOOD to BAD, or from GOOD to
UNCERTAIN. It is important that the control strategy that uses the PV also monitors the STATUS to take
appropriate action when the STATUS changes from GOOD to either BAD or UNCERTAIN.
Status options
Status options (status_opts) supported by the AI block are shown below:
Propagate fault forward
If the status from the sensor is Bad, Device failure or Bad, Sensor failure, propagate it to OUT without
generating an alarm. The use of these sub-status in OUT is determined by this option. Through this
option, the user determines whether alarming (sending of an alert) will be done by the block or
propagated downstream for alarming.
Uncertain if limited
Set the output status of the Analog Input block to uncertain if the measured or calculated value is limited.
BAD
Set the output status to Bad if the sensor is violating a high or low limit.
Uncertain if man mode
Set the output status of the analog Input block to uncertain if the actual mode of the block is Man.
Note
The instrument must be in out of service mode to set the status option.
4.9.6

Advanced features

The following parameters provide the capabilities to drive a discrete output alarm in the event that a
process alarm (HI_HI_LIM, HI_LIM, LO_LO_LIM, LO_LIM) has been exceeded.
ALARM_TYPE
ALARM_TYPE allows one or more of the process alarm conditions (HI_HI_LIM, HI_LIM, LO_LO_LIM,
LO_LIM) detected by the AI function block to be used in setting its OUT_D parameter.
OUT_D
OUT_D is the discrete output of the AI function block based on the detection of process alarm
condition(s). This parameter may be linked to other function blocks that require a discrete input based
on the detected alarm condition.
Configuration
Configuration
April 2017
155