Flowserve 3400IQ Digital Positioner - Manual (Page 34)

Logix 3400IQ Digital Positioner FCD LGENIM3402-00 – 0/07
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The Logix 3400IQ digital positioner can be designated as a LAS so that, in the event of a failure of the
primary LAS, control in the field could continue.
Please note that the Logix 3400IQ digital positioner in not designed to be the primary LAS, and,
therefore, the LAS capability in the positioner is regarded as a backup LAS. In some remote applica-
tions where there is no host computer continuously connected this device may be configured as the
primary LAS.
The LAS may be disabled by defining the Logix 3400IQ as a Basic device in the host system.
Special Non-volatile Parameter and NVM Wear Out
All function block parameters designated as non-volatile (N) in the FF specifications are updated
to non-volatile memory (NVM) on a periodic basis. NV_CYCLE_T parameter in the resource block
specifies this update interval.
To provide predictable restart behavior in the transmitter, the following non-volatile parameters are
updated to NVM each time they are written over the fieldbus.
MODE.TARGET for all blocks
SP.VALUE for the PID block
SP and OUT in the AO block
Since these are user-written parameters, additional updates to NVM contribute negligibly to NVM
wear-out. However, users are cautioned not to construct control configurations where the above
parameters are written continuously (via a computer application for example) or at rates greater than
the NV_CYCLE_T interval. This consideration will help minimize the possibility of NVM wear-out.
In the case of MODE, this should not be a problem. When users wish to provide setpoints to the PID
block via a computer application, users should use RCAS mode with its corresponding set-point
value RCAS_IN. RCAS_IN is updated only at the NV_CYCLE_T update rate and this mode supports
full shedding functionality and PID initialization necessary for a robust application.
6.5 Setting Write-Protect Feature
Write-protect Feature
The Logix 3400IQ digital positioner is available with a write protect feature. It consists of a dip switch
located on the device’s electronics board that can be set to enable read only access (write-protect) to
the device’s configuration. When the dip switch is in the “On” position and the corresponding device
parameter is set, the device’s configuration parameters and calibration data can only be read or
viewed, (device configuration is write protected).
ATTENTION: The dip switch is factory set for read- and write-access (not write-protected)
“Off” position. (If the dip switch is in the “On” position, the positioner must be powered
down before changing the dip switch.)
NOTE: The write protect dip switch is used in conjunction with the FEATURE_SEL parameter and is
explained below.
Refer to the following steps to set the write protect dip switch.
1. Remove power to Logix 3400IQ.
2. Loosen cap lock and unscrew the main housing cover of housing.
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