Owner's manual

3-5
Analog Output (AO) Function Block
Action On Fault Detection To define the state to which you wish the valve to enter when the
CAS_IN input detects a bad status and the block is in CAS mode,
configure the following parameters:
FSTATE_TIME: The length of time that the AO block will wait to
position the OUT value to the FSTATE_VAL value upon the detection
of a fault condition. When the block has a target mode of CAS, a fault
condition will be detected if the CAS_IN has a BAD status or an
Initiate Fault State substatus is received from the upstream block.
FSTATE_VAL: The value to which the OUT value transitions after
FSTATE_TIME elapses and the fault condition has not cleared. You
can configure the channel to hold the value at the start of the failure
action condition or to go to the failure action value
(FAIL_ACTION_VAL).
Block Errors The following conditions are reported in the BLOCK_ERR attribute:
Input failure/process variable has Bad status – The hardware is
bad, the Device Signal Tag (DST) does not exist, or a BAD status is
being simulated.
Out of service – The block is in Out of Service (O/S) mode.
Output failure – The output hardware is bad.
Readback failed – The readback failed.
Simulate active – Simulation is enabled and the block is using a
simulated value in its execution.
Modes The Analog Output function block supports the following modes:
Manual (Man) – You can manually set the output to the I/O channel
through the OUT attribute. This mode is used primarily for
maintenance and troubleshooting.
Automatic (Auto) – The block output (OUT) reflects the target
operating point specified by the setpoint (SP) attribute.
Cascade (Cas) – The SP attribute is set by another function block
through a connection to CAS_IN. The SP value is used to set the OUT
attribute automatically.
RemoteCascade (RCas) – The SP is set by a host computer by writing
to the RCAS_IN parameter. The SP value is used to set the OUT
attribute automatically.
Out of Service (O/S) – The block is not processed. The output channel
is maintained at the last value and the status of OUT is set to Bad: Out
of Service. The BLOCK_ERR attribute shows Out of Service.
Initialization Manual (Iman) – The path to the output hardware is
broken and the output will remain at the last position.
Local Override (LO) – The output of the block is not responding to
OUT because the resource block has been placed into LO mode or fault
state action is active.
The target mode of the block may be restricted to one or more of the
following modes: Man, Auto, Cas, RCas, or O/S.