Emerson Rosemount 375, User Manual, Page: 65 / 140

Fieldbus Functionality 4-3
LAS Hierarchy
When a 375 Field Communicator is connected to a live
fieldbus segment, it joins the fieldbus segment but not as
the LAS. This means the 375 Field Communicator can
view and edit device parameters, but the control of the
segment is still handled by the node that is designated
the LAS for the segment. You can also read and write if
there is another LAS. Prior to connecting to a host
system, review the 375 Field Communicator Host
System Interoperability on www.fieldcommunicator.com.
Device
Interoperability
The 375 Field Communicator is designed to operate with
a wide range of F
OUNDATION
fieldbus devices
independent of device manufacturer. Device
interoperability is achieved through the use of Device
Description Language (DDL) technology supported by
the Fieldbus Foundation.
Basic testing is performed on all device descriptions. In
addition, each device manufacturer is asked to certify
that they have thoroughly tested their devices with the
375 Field Communicator. If certification is not received, a
warning message will display when you attempt to
access an untested device.
ST_REV
ST_REV is a block parameter that increments each time
a block configuration has changed. While a list of
parameters is displayed, the 375 Field Communicator
continuously reads the ST_REV of that particular block.
If it sees the ST_REV counter has incremented, it knows
that there has been a change to the block, and it
automatically refreshes (rereads) all of the block
parameters. Thus, there would only be a very short
period of time before a change made by another host
would appear on the 375 Field Communicator display.