Link Active Scheduler (Las); Block Installation - Emerson Rosemount 644 FOUNDATION Reference Manual

Reference Manual
00809-0400-4728, Rev CA
Note
When an upstream block is set to OOS, this will impact the output status of all downstream blocks. The
figure below depicts the hierarchy of blocks:
2.3.4

Link Active Scheduler (LAS)

The Rosemount 644 can be designated to act as the backup LAS in the event that the designated LAS is
disconnected from the segment. As the backup LAS, the Rosemount 644 will take over the management
of communications until the host is restored.
The host system may provide a configuration tool specifically designed to designate a particular device
as a backup LAS. Otherwise, this can be configured manually as follows:
1. Access the Management Information Base (MIB) for the Rosemount 644.
To activate the LAS capability, write 0x02 to the BOOT_OPERAT_FUNCTIONAL_CLASS object
(Index 605). To deactivate, write 0x01.
2. Restart the device.
2.3.5

Block installation

Rosemount devices are pre-configured with function blocks at the factory, the default permanent
configuration for the Rosemount 644 is listed below. The Rosemount 644 can have up to 10 additional
instantiated function blocks.
Two AI blocks (tag names AI 1300, AI 1400)

One proportional/integral/derivative block (tag name PID 1500)

The Rosemount 644 supports the use of function block Instantiation. When a device supports block
instantiation, the number of blocks and block types can be defined to match specific application
needs.The number of blocks that can be instantiated is only limited by the amount of memory within the
device and the block types that are supported by the device. Instantiation does not apply to standard
device blocks like the resource, sensor transducer, LCD transducer, and advanced diagnostics blocks.
By reading the parameter "FREE_SPACE" in the Resource block you can determine how many blocks you
can instantiate. Each block that you instantiate takes up 4.5 percent of the "FREE_SPACE."
Block instantiation is done by the host control system or configuration tool, but not all hosts are required
to implement this functionality. Please refer to your specific host or configuration tool manual for more
information.
Configuration
Transducer
Resource block
block
Other
Analog input
function
(AI block)
blocks
Configuration
September 2018
7