AO Function Block
December 2009
4-75
AO Block Parameter List
Read/Write Capability: RO − Read Only, RW − Read Write
Mode: The block mode(s) required to write to the parameter
Double indentation and shaded Index Number indicates sub-parameter
Table 4-24. Analog Output Function Block Parameter Definitions
Label
PARAMETER_NAME
Index
Number
RO /
RW
Block
Mode
Range
Initial
Value
Description
Static Revision
ST_REV
1 RO N/A 0 to 65535 0
Data Type: Unsigned16
The revision level of the static data associated
with the function block. The revision value will be
incremented each time a static parameter value in
the block is changed.
Tag Description
TAG_DESC
2 RW ALL 7 bit ASCII Spaces
Data Type: Octet String
The user description of the intended application of
the block.
Strategy
STRATEGY
3 RW ALL 0 to 65535 0
Data Type: Unsigned16
The strategy field can be used to identify grouping
of blocks. This data is not checked or processed
by the block.
Alert Key
ALERT_KEY
4 RW ALL 1 to 255 0
Data Type: Unsigned8
The identification number of the plant unit. This
information may be used in the host for sorting
alarms, etc.
Block Mode
MODE_BLK
5
Data Type: DS-69
Valid Bits: 7: OOS, 6: IMAN, 5: LO, 4: MAN, 3:
AUTO, 2: CAS, 1: RCAS
The actual, target, permitted, and normal modes
of the block.
Target: The requested block mode
Actual: The current mode of the block
(Note: Bit 6 (IMAN) is valid for ACTUAL only)
Permitted: Allowed modes for Target
Normal: Most common mode for Target
TARGET
5.1 RW ALL
OOS
MAN
AUTO
AUTO-CAS
AUTO-RCAS
OOS until
block is
configured,
then last valid
target
ACTUAL
5.2 RO ALL OOS
PERMITTED
5.3 RW ALL
OOS+MAN+AUTO+
CAS+RCAS
OOS+MAN+
AUTO+
CAS+RCAS
NORMAL
5.4 RW ALL AUTO
Block Error
BLOCK_ERR
6 RO N/A
1: Block Configuration
Error
3: Simulate Active
4: Local Override
5: Device Fault State
Set
8: Output Failure
14: Power-up
15: Out-of-Service
Dynamic
Data Type: Bit String (2 byte)
0=inactive
1=active
This parameter reflects the error status
associated with the hardware or software
components associated with a block. It is a bit
string, so that multiple errors may be shown. See
table 4-23.
Process Variable
PV
7 RO N/A
PV Status set equal
to READBACK status
Dynamic
Data Type: DS-65
The process variable used in block execution.
This value is converted from READBACK to show
the actuator position in the same units as the
setpoint value.
Set Point
SP
8
OOS
MAN
AUTO
PV_SCALE +/− 10% Dynamic
Data Type: DS-65
The SP of the analog block. Can be derived from
CAS_IN, RCAS_IN in normal modes, or can track
PV in MAN, IMan or LO modes. IO_OPTS is used
to determine value of SP in MAN, IMan or LO. If
no IO_OPTS for SP tracking are set, SP will
freeze when mode changes from CAS or RCAS.
Output
OUT
9
MAN
OOS
OUT_SCALE +/− 10% Dynamic
Data Type: DS-65
The primary value and status calculated by the
block in Auto mode. OUT may be set manually in
Man mode.
−Continued−
4
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