Reference Manual
00809-0400-4728, Rev AA June 2011
Rosemount 644
Resource Block
The block supports two forms of the PID equation: Standard and Series. You can choose the appropriate equation using the MATHFORM parameter. The Standard ISA PID equation is the default selection.
FEATURES and FEATURES_SEL
The parameters FEATURES and FEATURE_SEL determine optional behavior of the 644.
FEATURES
The FEATURES parameter is read only and defines which features are supported by the 644. Below is a list of the FEATURES the 644 supports.
UNICODE
All configurable string variables in the 644, 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 644 supports alert reports. The Reports option bit must be set in the features bit string to use this feature. If it is not set, the host must poll for alerts.
SOFT W LOCK
Inputs to the security and write lock functions include the 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. During this time, the block will function normally updating inputs and outputs and executing algorithms. 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 the software write lock or no write lock capability. In order to enable the software write lock, the SOFT_W_LOCK bit must be set in the FEATURE_SEL parameter. Once this bit is set, the WRITE_LOCK parameter may be set to “Locked” or “Unlocked.” Once the WRITE_LOCK parameter is set to “Locked” by the software, all user requested writes as determined by the DEFINE_WRITE_LOCK parameter shall be rejected.
The DEFINE_WRITE_LOCK parameter allows the user to configure whether the write lock function will 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.
N/A = No blocks are blocked
Physical = Locks resource and transducer block Everything = Locks every block.