Status Propagation - Emerson Fisher Fieldvue DVC6030f Instruction Manual

DVC6000f Series
B2712-1 / IL
Fieldbus Foundation specifications for a more detailed
description. The following describes how the
transducer block passes status information to the AO
block. For information on status handling by the
function blocks within the digital valve controller, refer
to the Detailed Setup section.

Status Propagation

The transducer block accepts the output from the AO
block or DO block if the output parameter status is
Good (Non-cascade) or Good (Cascade). When the
AO or DO block is Out of Service the output
parameter status is Bad. In this case, the transducer
block holds the last value.
A
If the transducer block actual mode is Out of Service,
the AO block READBACK parameter status is
Bad−Out of Service. This could be caused by a Failed
Alert. If a Failed Alert is active, the block error
parameter (parameter name BLOCK_ERR) for the
Resource block will indicate Device Needs
Maintenance Now. For more information on the
Resource and Transducer block error indications, refer
to the Viewing Device Information section of this
manual.
If the transducer block is functioning correctly the AO
block READBACK parameter status is Good
(Non-cascade)−Non-specific. If a Maintenance or
Advisory alert is active the substatus will reflect a
Unacknowledged or Active advisory alert. When a
Maintenance or Advisory alert is active, the block error
for the resource block indicates Device Needs
Maintenance Soon.
A-6
LAS
LINK MASTER
LAS = Link Active Scheduler
Figure A-3. Simple Single-Link Fieldbus Network
Fieldbus Segment
BASIC DEVICES
Limit Propagation
The following describes limit propagation:
AO Block
D If the valve position is below the low cutoff value,
the AO block READBACK status limit is
LOW_LIMITED.
D If the valve position is above the high cutoff
value, the AO block READBACK status limit is
HIGH_LIMITED.
D If the transducer block actual mode is Auto and
the above conditions are not true, the AO block
READBACK status limit is NOT_LIMITED.
D If the transducer block actual mode is Out of
Service, the AO block READBACK status limit is
CONSTANT.
DO Block
D If the transducer block actual mode is Auto, the
DO block READBACK_D status is NOT_LIMITED.
D If the transducer block actual mode is Out of
Service, the DO block READBACK_D status is
CONSTANT.
The control strategy should be configured to monitor
the Analog Output block status and take action where
appropriate when the status is no longer Good.
Network Communication
Figure A-3 illustrates a simple fieldbus network
consisting of a single segment.
Device Addressing
Fieldbus uses addresses between 0 and 255.
Addresses 0 through 15 are typically reserved for
March 2006