Yokogawa YVP20S - Manual (Page 41)

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<Toc> <Ind> <5. FOUNDATION FIELDBUS OVERVIEW>
IM 21B04C50-01E
5.5 Changing Operational States
The Foundation fieldbus Application process specifies the mode handling for interoperable
function blocks. It also specifies which mode a block must be in when each parameter is
written. ValveNavi provides an intelligent, optimized process for managing configuration
and calibration changes. For efficiency, it does not place blocks into Out Of Service mode
unless the parameter requires OOS. It analyzes the requested changes and then sets the
correct mode for each affected function block. The actual block modes are displayed in the
IVI.
The Foundation fieldbus specifies a mechanism for transferring between function block
modes. The user declares a target for the block mode, but the actual mode is set by the
block in accordance with rules. The rules allow modes based on the quality of input data
and quality of the connection to the process. YVP function blocks comply with the FF rules.
ValveNavi sets target modes for individual function blocks as required by configuration,
calibration, diagnostics and other services. It sets target modes for group of function blocks
to achieve three operational states of the positioner: Out of Service, Manual, and Normal.
(1) Changing Target Operational State
When a configuration or other process requires any of the affected function blocks to go
into OOS mode, ValveNavi opens a Warning dialog as shown in Figure 5.13
Figure 5.13 Out Of Service State Change Warning
(2) Changing to Auto from OOS
In OOS, the YVP can be switched to Auto in order to return the device to the previous Auto
state by clicking on Auto. In the event the user has selected “bumpless transfer” the device
will execute the bumpless transfer routine.