Emerson 475, User Manual

Page: 61 / 114

Fieldbus Functionality
4-9
Block 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 types of modes that may
also be supported are Cas, RCas, ROut, IMan and LO.
Types of Modes
For the procedures described in this manual, it is 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.
MAN
In this mode, the output of the block can be manually overwritten for testing
purposes.
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
other blocks is “BAD”. Before you make 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.
Mode Parameters
Mode parameters are used to change the block mode from one state to another. There
are four types of mode parameters: Target, Actual, Permitted, and Normal.
The Target mode is the mode assigned to a block and is used to change a block to a
desired mode.
The Actual mode is the current mode of the block.
The Permitted mode lists the modes that are allowed for a block. Setting the Permitted
modes prevents unauthorized changes to the operating mode of a block. To do this,
configure the Block:Mode Permitted parameter to allow only the desired operating
modes. It is recommended to always select OOS as one of the Permitted modes.
The Normal mode is the mode the block should be set to during normal operation
conditions.
Locate Mode Parameters
In the resource and transducer blocks, the mode parameters are normally found in the
Process menu. In all other function blocks, they are found in the Common Config
menu. The mode parameters are also included in the All parameter list; see “Device
Blocks” on page 4-11.
You can view and edit the Target mode parameter by tapping the MODE button in the
menus.