Fisher FIELDVUEDVC6200f Instruction Manual page 303

Instruction Manual
D103412X012
Mode Handling
Shed Options — RCAS Mode Only
Shed from or climb to a remote mode is determined by the parameter SHED_OPT [23]. A block climbs and sheds
through the same path. For example, if SHED_OPT [23] specifies that a block should shed to Auto, then, if the block
target mode is set to RCas, the block goes through Auto on the way to RCas. You can configure the shed option as
follows:
Shed With Return Options
Remote cascade connection failure shifts actual mode but keeps trying to restore remote cascade (in other words, the
remote cascade target mode stays in effect).
Normal—On failure of a remote cascade connection, the block attempts to attain the highest permitted non‐remote
mode until remote cascade is restored. Cas is the highest permitted non‐remote mode and Auto is is the next
permitted non‐remote mode. If Cas or Auto are not available, the block will shed by default to Man.
Retained Target—The retained target mode is the target mode for the block before changing the target mode to a
remote mode. On failure of a remote cascade connection, the block attempts to attain the retained target mode.
Auto—On failure of a remote cascade connection, the block attempts to attain Auto, if permitted, until remote
cascade is restored.
Man—On failure of a remote cascade connection, the block sheds to Man until a remote cascade connection is
restored.
Shed With No Return Options
For any shed with no return option, the target mode changes as determined by the option. Therefore, there is no
attempt to restore the connection following failure. The behavior on change to the remote cascade target mode is
identical to that for Shed With Return Options.
Normal—On failure of a remote cascade connection, the block sets the target mode to the highest permitted
non‐remote mode. Cas is the highest permitted non‐remote mode and Auto is is the next highest permitted
non‐remote mode. If Cas or Auto are not available, the block will shed by default to Man.
Retained Target—The retained target mode is the target mode for the block before changing the target mode to a
remote mode. On failure of a remote cascade connection, the block sets the target mode to the retained target mode.
Auto—On failure of a remote cascade connection, the block sets the target mode to Auto, if permitted.
Man—On failure of remote cascade connection, the block sets the target mode to Man, if permitted.
The user may configure SHED_OPT [23] so that it calls for a target mode that is not permitted. When doing this, the
mode logic uses the following rules as applied by the remote logic:
D Shed logic never results in a non‐permitted target mode.
D Shed logic never attempts to attain an actual mode of Auto or Cas if that mode is not permitted.
DVC6200f Digital Valve Controller
DO Function Block
February 2017
303