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Reference Manual
00809-0100-4696, Rev AA
September 2004
Rosemount 848L
3-2
GENERAL BLOCK
INFORMATION
Modes The Resource, Transducer, and all function blocks in the device have modes
of operation. These modes govern the operation of the block. Every block
supports both automatic (AUTO) and out of service (OOS) modes. Other
modes may also be supported.
Changing Modes
To change the operating mode, set the MODE_BLK.TARGET to the desired
mode. After a short delay, the parameter MODE_BLOCK.ACTUAL should
reflect the mode change if the block is operating properly.
Permitted Modes
It is possible to prevent unauthorized changes to the operating mode of a
block. To do this, configure MODE_BLOCK.PERMITTED to allow only the
desired operating modes. It is recommended to always select OOS as one of
the permitted modes.
Types of Modes
For the procedures described in this manual, it will be helpful to understand
the following modes:
AUTO
The functions performed by the block will execute. If the block has any
outputs, these will continue to update. This is typically the normal
operating mode.
Out of Service (OOS)
The functions performed by the block will not execute. If the block has any
outputs, these will typically not update and the status of any values passed
to downstream blocks will be “BAD”. To make some changes to the
configuration of the block, change the mode of the block to OOS. When
the changes are complete, change the mode back to AUTO.
MAN
In this mode, variables that are passed out of the block can be manually
set for testing or override purposes.
Other Types of Modes
Other types of modes are Cas, RCas, ROut, IMan and LO. Some of these
may be supported by different function blocks in the Rosemount 848L. For
more information, see the Function Block manual, document
00809-0100-4783.
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:
Resource
Block
Transducer
Block
Discrete Input
(DI Block)
Other
function
blocks