KROHNE OPTISONIC 3400 EN - Manual (Page 121)

DESCRIPTION OF HART INTERFACE
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OPTISONIC 3400
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9.5 Remote operation
In addition to the local user interface panel the device may be operated remotely via the
communication interface. There are different operating tools including small handhelds and
large integrated maintenance systems. For adaptation to different devices two main
technologies are used: The Device Description (DD) and the Field Device Tool Device Type
Manager (FDT DTM). Both a DD and a DTM contain the description of a device's user interface,
parameter database and communication interface. After being installed in an operating tool they
allow access to device specific data. In the DD environment an operating tool is usually referred
to as "host"; in the FDT DTM environment it is called "frame application" or "FDT container".
A DD is sometimes also referred to as EDD for Enhanced Device Description. This emphasizes
some enhancements in specification like e.g. GUI support but doesn’t imply a new technology.
For improving interoperability between DD hosts standard menu entry points have been
specified:
• Root Menu
Default top level menu for DD host applications with limited display space (e.g. handhelds).
• Process Variables Root Menu
Provides process measurements and set points. For GUI based DD host applications.
• Diagnostic Root Menu
Shows device state and diagnostic information. For GUI based DD host applications.
• Device Root Menu
Provides access to all field device capabilities. For GUI based DD host applications.
• Offline Root Menu
Provides access to all field device capabilities that can be manipulated while the host
application is not connected to the field device.
For detailed information about the standard menus refer to refer to HART Menu Tree; UFC400 on
page 126.
The support of the standard menu entry points by the different DD hosts is described next.
9.5.1 Online/offline operation
DD hosts have different characteristics and support different operating modes for configuring
devices, online and offline mode.
In online mode the host application can currently communicate with the device. The device can
immediately check and perform configuration changes and update dependent parameters in
case.
In offline mode the host application works only with a copy of the device's configuration data set
and the DD needs to imitate the device's checks and updates.
Unfortunately the DD isn't informed by the host whether it is running in online or offline mode. In
order to avoid interference between update functionality of the DD and the device there is a local
parameter "Online Mode?" in the "Detailed Setup / HART" menu which can be set accordingly by
the user.