Flowserve MX FOUNDATION Fieldbus Field Unit - Manual (Page 33)

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MX/QX FOUNdaTION Fieldbus Field Unit FCd LMENIM2330-01 – 08/11
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This feature requires the installation of a hardware jumper on the MX/QX FF unit, located on header
X5 Pins 7 and 8.
3.6 Discrete Output (DO) Function Block
The Discrete Output (DO) function block processes a single discrete setpoint and outputs it to a
specified I/O channel to produce an output signal. The DO block supports mode control, output
tracking, and simulation. There is no process alarm detection in the block. In operation, the DO func-
tion block determines its setpoint, sets the output, and, as an option, checks a readback signal from
the field device to confirm the physical output operation.
There are two DO blocks in the Limitorque actuator control system, and three channels:
Chan. No.9 — DO_POSITION_CHAN — Command Stop/Open/Close
Chan. No.10 — DO_ESD_CHAN — Command Emergency Shutdown
Chan. No.11 — DO_RELAY_CHAN — Command energize relays
Figure 3.5 – Discrete Output Function Block
To set the DO block output, the operator first sets the mode to define how the block obtains its
output. In Cascade Mode, the setpoint equals the input value from another block. In Auto Mode, the
setpoint is written to the block. In Manual Mode, the setpoint is written to the Output. In Remote
Cascade Mode, the setpoint is determined by a host computer or DCS that writes to the RCAS input.
Inputs
CAS_IN_D is the remote (cascade) setpoint value from another function block.
RCAS_IN_D is a target setpoint and status provided by a supervisory host to a discrete control or
output block.
Outputs
OUT_D is the discrete output value and status.
BKCAL_OUT_D is the back calculation output value and status required by the BKCAL_IN_D input of
another block for output tracking.
OUT_D
Discrete Output Block
CAS_IN_D
RCAS_IN_D
Setpoint Optional
Invert
Output
MODE
SHED_OPT
SP_D
Optional
Invert
PV_D
Fault State
FSTATE_TIME
FSTATE_VAL_D
Simulate
SIMULATE_D
CHANNEL
DATA
READBACK_D
BKCAL_OUT_D
RCAS_OUT_D
(Transducer)