Emerson Rosemount, Справочное руководство

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144
Reference Manual
00809-0100-4021, Rev GC
Section 4: F
OUNDATION
fieldbus Configuration
April 2014
Foundation™ fieldbus configuration
4.5 Resource block
4.5.1 Features and Features_Sel
The FEATURES and FEATURE_SEL parameters determine optional behavior of the 3144P.
FEATURES
The FEATURES parameter is read only and defines which features are supported by the 3144P.
The list of FEATURES the 3144P supports is listed below.
UNICODE
All configurable string variables in the 3144P, except tag names, are octet strings. Either ASCII or
Unicode may be used. If the configuration device is generating Unicode octet strings, you must
set the Unicode option bit.
REPORTS
The 3144P supports alert reports. To use this feature, the Reports option bit must be set in the
features bit string. If it is not set, the host must poll for alerts.
SOFT W LOCK and HARD W LOCK
Inputs to the security and write lock functions include the hardware security switch, the
hardware and software write lock bits of the FEATURE_SEL parameter, the WRITE_LOCK
parameter, and the DEFINE_WRITE_LOCK parameter.
The WRITE_LOCK parameter prevents modification of parameters within the device except to
clear the WRITE_LOCK parameter. The block will function normally updating inputs and outputs
and executing algorithms while WRITE_LOCK is in use. When the WRITE_LOCK condition is
cleared, a WRITE_ALM alert is generated with a priority that corresponds to the WRITE_PRI
parameter.
The FEATURE_SEL parameter enables the user to select a hardware or software write lock or no
write lock capability. To use the hardware security function, enable the HW_SEL bit in the
FEATURE_SEL parameter. When this bit has been enabled, the WRITE_LOCK parameter becomes
read only and reflects the state of the hardware switch. In order to enable the software write
lock, the SW_SEL bit must be set in the FEATURE_SEL parameter. Once this bit is set, the
WRITE_LOCK parameter may be set to “Locked” or “Not Locked.” Once the WRITE_LOCK
parameter is set to “Locked” by either the software or the hardware lock, all user requested
writes as determined by the DEFINE_WRITE_LOCK parameter will be rejected.
The DEFINE_WRITE_LOCK parameter allows the user to configure whether the write lock
functions (both software and hardware) control writing to all blocks, or only to the resource and
transducer blocks. Internally updated data such as process variables and diagnostics will not be
restricted by the security switch.
The following table displays all possible configurations of the WRITE_LOCK parameter.
FEATURE_SEL
HW_SEL bit FEATURE_SEL
SW_SEL bit SECURITY
SWITCH
WRITE_LOCK
WRITE_LOCK
Read/Write DEFINE_WRITE
_LOCK Write access
to blocks
0 (off) 0 (off) N/A 1 (unlocked) Read only N/A All
0 (off) 1 (on) N/A 1 (unlocked) Read/Write N/A All
0 (off) 1 (on) N/A 2 (locked) Read/Write Physical Function
Blocks only
0 (off) 1 (on) N/A 2 (locked) Read/Write Everything None