Flowserve MX FOUNDATION Fieldbus Field Unit - Manual (Page 30)

MX/QX FOUNdaTION Fieldbus Field Unit FCd LMENIM2330-01 – 08/11
30
Filter
The PV filter, whose time constant is PV_FTIME, is applied to the PV, and not the FIELD_VAL.
Simulation
Simulation is used to support testing. Simulation can be enabled through the configuration tool and
allows the manual entry of a value for a measurement and its status.
This feature requires the installation of a hardware jumper on the MX/QX FF unit, located on header
X5 Pins 7 and 8.
3.4 Analog Output Function Block
The Analog Output (AO) block assigns an output value to a field device through a specified transducer
block I/O channel. The block supports mode control, signal limiting, rate limiting, signal status
calculation, and simulation. There are provisions to ensure bumpless mode transfer when this block
is part of a control loop.
There is one AO block in the Limitorque actuator control system:
Channel No.1 — AO_CTRL_VALVE_FLOW_CHAN — Desired valve position %
Figure 3.3 – Analog Output Block
The output can be set in four ways. In Manual Mode, the output can be set by the user, and this
value is independent of the Setpoint. In Automatic Mode, the output is set by the Setpoint value in
engineering units and the I/O options parameter. In Cascade Mode, the Cascade Input value from
another block is used to update the Setpoint. In Remote Cascade Mode, the setpoint comes from a
remote computer or DCS. The Setpoint value can be limited, and also the rate at which the setpoint
output changes can be limited.
To provide bumpless transfer on mode changes and windup protection if there is an upstream PID
block, the Back Calculation Out parameter is used, and various block I/O options.
Inputs
CAS_IN is the remote setpoint from another function block.
OUT (to
Transducer
block)
Analog Output Block
CAS_IN
RCAS_IN
Setpoint
SP_RATE_DN
SP_RATE_UP
SP_HI_LIM
SP_LO_LIM
Out Convert
PV_SCALE
XD_SCALE
Output
MODE
SHED_OPT
SP
PV Convert
XD_SCALE
PV_SCALE
PV
Fault State
FSTATE_TIME
FSTATE_VAL
Simulate
SIMULATE
CHANNEL
DATA (from
transducer)
READBACK
BKCAL_OUT
RCAS_OUT