Fisher FIELDVUE DVC6200f Instruction Manual page 164

Detailed Setup—OS Function Block
July 2013
D Out of Service (OOS)—The block is not processed. FIELD_VAL and PV are not updated and the OUT status is set to
Bad: Out of Service. The BLOCK_ERR parameter shows Out of Service. In this mode, you can make changes to all
configured parameters.
By using permitted mode the target mode of a block may be restricted to one or more of the following modes: Cas,
Auto or OOS.
Note
The output splitter function block must be in Auto for the mode to go to CAS.
D Initialization Manual (IMan)—The output path is not complete (for example, the cascade-to-slave path might not be
open). In IMan mode, OUT tracks BKCAL_IN, which allows for bumpless transfer of control.
D Automatic (Auto)—The block outputs (OUT_1 and OUT_2) reflect the target operating point specified by the
setpoint (SP) parameter.
D Cascade (Cas)—The SP parameter is set by another function block through a connection to CAS_IN. The SP value is
used to set the OUT parameters automatically. This is the most frequently used mode in this block.
The block's normal mode is Cascade (Cas). You can isolate the block for testing by using Automatic (Auto) mode and
adjusting the setpoint.
When a block attached to an output requests initialization, one of the following actions might occur:
D When the other output is not in Cas mode, the block attached to the input is initialized.
D When the other output is in Cas mode, this output returns to the value calculated from its slope in a specified time
period.
Status Handling
Sub‐status value received at CAS_IN [14] is passed to both outputs, except for those used in the cascade handshake.
An IFS goes to both outputs. The status option IFS if Bad CAS_IN is available.
If the Status Option to Propagate failure is set, the block propagates device failure only if both BKCAL_IN show failed
status. Otherwise the upstream cascade would be broken by a failure at either output.
The statuses of OUT_1 [8] and OUT_2 [9] are determined by the statuses of BKCAL_IN_1 and BKCAL_IN_2 and the
actual mode of the block.
When a BKCAL_IN input sees that its downstream block is not in Cas mode, the Splitter function block sets the
corresponding OUT value to the BKCAL_IN value. However, this may not be the same value that is calculated by the
splitter algorithm. When the mode of the downstream block is changed to Cas, the difference between the calculated
output and the back‐calculation input is computed and the difference is added to the calculated output. Next, the
difference is reduced to zero over the time defined by the BAL_TIME parameter.
When both BKCAL_IN_1 and BKCAL_IN_2 indicate that the downstream blocks are not in Cas mode or have Bad status,
the first downstream block that goes to Cas mode causes the upstream block to initialize so that there is no difference
between the calculated output and the back‐calculation input. This provides bumpless transfer for the first
downstream block.
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Instruction Manual
D103412X012