Flowserve 3400IQ Digital Positioner - Manual (Page 53)

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Logix 3400IQ Digital Positioner FCD LGENIM3402-00 – 0/07
flowserve.com
minimum 10,000,000 write cycle endurance. Even though this is a very high number that would
typically never be reached during the operational life of the device, a misbehaving host configura-
tion routing could drive up the number or write cycles very quickly, and should be corrected as all
devices in the configuration will be adversely affected by this continuous download.
Signatures See Section 10.13, Initiating a Valve Signature for more details on using the signature
acquisition functions of the Logix 3400IQ digital positioner.
Custom Characterization See Section 10.11, Stroke Characterization for more details on using the
custom characterization features of the Logix 3400IQ digital positioner.
8.6 Analog Output Function Block
AO Block Description
The Analog Output function block serves as the external interface for the transducer function block.
The value of SP is used to produce the OUT value which is then sent to the transducer block to
specify the valve position. PV reflects the actual valve position reported by the transducer block.
The AO function block operates on the output value from a control block [such as PID] and performs
the following primary functions (most can be user configured):
Set-point source selection limiting
Units conversion
Fault state action
Position read back
Alarming
Mode control
Output calculation
The database contains the standard AO block database, as defined in the FF FBAP specifications.
Flowserve product extensions are specified in the Logix 3400IQ digital positioner parameter
dictionary and are described below.
The interface to the AO block contains the following:
Execute function block
Database read access
Alarm acknowledgment
Database write access
AO Block Connections
CAS_IN is the only linkable input parameter and is used with a PID function block for direct cascade
connection. RCAS_IN is a contained input parameter used for remote cascade connection.
OUT and BKCAL_OUT are linkable output parameters. RCAS_OUT is a contained output parameter for
remote cascade connection.
The OUT parameter of the AO block is used to set the FINAL_POSITION_VALUE in the transducer
block, as modified by the FINAL_VALUE_RANGE.
READBACK_OUT tracks the valve position in percent.
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