Revision 4 Foundation Fieldbus RMA803 Remote Indicator User's Guide Page 37
SOFT W LOCK and HARD W LOCK
There are two types of write locks: Hardware write lock and Software write lock. The software write
lock is used to lock the device. The software write lock does not need a jumper. A hardware write
lock is provided with a jumper in the device to perform the write lock operation.
If the WRITE_LOCK parameter is set, it prevents any external change to the static or non-volatile
database in the Function Block Application of the resource. Block connections and calculation
results proceeds normally but the configuration is locked. A hard write lock is provided by a jumper
in the device as indicated in the FEATURES bit string. Clearing WRITE_LOCK generates the
discrete alert WRITE_ALM at the WRITE_PRI priority.
If the soft write lock bit is not set as True in the features bit strings, the writing to the parameter
WRITE_LOCK is rejected by the device. For devices that support hard write lock and have the
associated FEATURE_SEL attribute enabled, the parameter WRITE_LOCK is only an indicator
of the state of write-lock. The writing to WRITE_LOCK is rejected by the device.
Software write lock
To activate write lock, the soft write lock supported bit in FEATURE_SEL must be set, and then
set the WRITE_LOCK to locked. To deactivate write lock, set the WRITE_LOCK to unlocked.
Hardware write lock
To activate write lock, the hard write lock supported bit in FEATURE_SEL must be set, and
additionally the write lock jumper must be in the correct position as determined by the manufacturer.
When this is detected by the device, WRITE_LOCK is set to locked. If hard write lock is enabled
in FEATURE_SEL, the configured value of soft write lock has no impact on device operation. To
deactivate write lock, the jumper must be changed as FEATURE_SEL is not writeable during write
lock. Once the device detects the change in jumper position, the write-lock is disabled and
WRITE_LOCK is set to 1.
Install Date
When the device is connected to the master/host, the time at which the device is powered up is taken
as the install date. It is a read-only parameter.
To Next Page
Loading...
