Flowserve 3400IQ - Manual (Page 28)

Logix 3400IQ Digital Positioner FCD LGENIM3403-00 – 11/07
Initiating a Valve Signature
A feature of the Logix 3400IQ digital positioner is the ability to capture and store a valve diagnostic signature
in the positioner’s volatile RAM. A signature is the collected data response of the valve to a pre-defined set
of operating conditions. This stored data can later be uploaded to the host system for analysis of potential
problems. By comparing a baseline signature (when the valve is new) to subsequent signatures at later
times, a rate of change can be tracked which can help predict possible faults in the valve before they
happen. This is called ‘predictive maintenance’.
NOTE: The purpose of the positioner is to act as the data acquisition device for the signature. Analysis of
the data is not done on the device, but in the supervisory system.
System Preparation
WARNING: By definition, the collection of the signature requires the unmanaged operation of the
positioner. Therefore, the process must be in a safe operating mode where unexpected movement of the
valve will not cause a hazardous condition.
Before a valve signature can be run, the Transducer block must out of service.
Table 3: Transducer Block Signature Parameters
Parameter Description Value-Meaning Comments
MODE_BLK The operatingmode of the
transducer block
Permitted Modes:
Auto - Auto (target mode)
OOS - Out of Service
The transducer block
must be in
the OOS
mode to perform a
signature
0 - VALVE INIT Initializes
valve for signature
capture.
Read-only
1 - STEP_RAMP Selects
which type of signature is
desired. Select for ramp
signature.
2 - SIG_COMPLETE
Status byte set when the
signature has been
completed, Read-only
4 - PRESS_MEAS
Selects if actuator
pressure readings are
desired as part of the
signature. Select for
readings
SIG_FLAGS Byte values which select
which signature options are
used
5 - BEGIN_SIG Set to
initiate the signature
routine.
Select the desired
signature
options and
then make sure the
signature parameters
are set to
the desired
operation before
beginning the
signature.
SIG_START Beginning position point (%)
for signature -10% to 110%
position range
Set higher than the stop
position
for a valve
closing signature.
SIG_STOP Ending position point (%) for
signature
-10% to 110% position
range Set lower than the
starting position
for a
closing signature
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