17
Manual Supplement
00809-0200-4853, Rev AB
Rosemount 3051S Series Pressure Transmitter
November 2017
Rosemount 3051S Series Pressure Transmitter
SPM_STATUS
Current state of the SPM diagnostic. Possible values for SPM status are as shown in Tab le 1 0.
In most cases, only one of the above SPM status bits will be active at one time. However, it is possible for
“Mean Change Detected” to be active at the same time as either “High Variation Detected” or “Low
Dynamics Detected” is active.
6.10 Plantweb alert
When any of the SPM detections (Mean Change, High Variation, or Low Dynamics) is active, a Fieldbus
Plantweb alert in the device “Statistical Process Monitor Trip” will be generated and sent to the host
system.
6.11 Trending statistical values in control system
SPM mean and standard deviation values may be viewed and/or trended in a Fieldbus host system
through the AI function blocks.
An AI Block may be used to read either the mean or the standard deviation from the ADB Block. To use
the AI Block to trend SPM data, set the CHANNEL parameter to one of the values in Tab le 11 :
The SPM Mean and Standard Deviation display units can be changed in the AI function blocks.
Table 10. SPM Diagnostic Current State
Status value Description
Inactive User Command in “Idle”, SPM not Enabled, or the function block is not scheduled.
Learning Learning has been set in the User Command, and the initial baseline values are being
calculated.
Verifying Current baseline values and previous baseline values are being compared to verify the
process is stable.
Monitoring Monitoring the process and no detections are currently active.
Mean Change
Detected
Alert resulting from the Mean Change exceeding the Threshold Mean Limit. Can be
caused by a set point change, a load change in the flow, or an obstruction or the
removal of an obstruction in the process.
High Variation
Detected
Alert resulting from the Stdev Change exceeding the Threshold High Variation value.
This is an indicator of increased dynamics in the process, and could be caused by
increased liquid or gas in the flow, control or rotational problems, or unstable pressure
fluctuations.
Low Dynamics
Detected
Alert resulting from the Stdev Change exceeding the Threshold Low Dynamics value.
This is an indicator for a lower flow, or other change resulting in less turbulence in the
flow.
Table 11. Valid SPM Channels for the AI Block
Channel SPM variable
12 Mean
13 Standard Deviation
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