Flowserve PMV D3 User Instructions page 22

(FF) Foundation Fieldbus function
blocks
Function blocks are sets of data sorted by function
and use. They can be connected to each other to
solve a control process, or to a controlling DCS.
To get a good introduction and understanding of
FF look at www.fieldbus.org and download the
"Technical Overview" from the About FF pages.
(TB) Transducer Block
The TB contains unit specific data. Most of the
parameters are the same as parameters found on
the display. The data and the order of data varies
between different products.
The AO-block setpoint (SP) and process value (PV)
parameters are transceived to the TB through a
channel. The TB has to be in AUTO for the AO-block
to be in AUTO.
The positioner has to be in menu-auto mode and in
service to be controlled from the fieldbus.
If the positioner is placed in menu-manual mode
then the transducer block will be forced to (LO)
local override. In this way an operator in the field
will be able to control the positioner from the
keypad, without affecting a control loop.
(RB) Resource Block
The RB is a set of parameters that looks the same
for all units and products. The values of the RB
define unit information that concerns the Fieldbus
Protocol such as MANUFAC_ID which informs
the unique manufacturer id. For Flowserve it is
0x464C53.
The RB has to be in AUTO for the AO-block to be
in AUTO.
(AO) Analogue Output Block
The AO follows Fieldbus Foundation's standard on
content and action. It is used for transferring (SP)
setpoints from the bus to the positioner.
CAS_IN (cascade input) and RCAS_IN (remote
cascade input) are selected as inputs to the AO
block depending on the MODE_BLK parameter. The
selected input will be relayed to the SP parameter of
the AO block. BKCAL_OUT (back calculated output)
PMV D3 Digital Positioner
is a calculated output that can be sent back to a
controlling object so that control bumps can be
avoided. Usually the BKCAL_OUT is set to be the
(PV) process value of the AO-block, i.e. the actual
measured position of the valve.
OUT is the primary calculated output of the AO
block. During a limited action (ramping) of the AO
block the RCAS_OUT parameter will supply the
final setpoint and the OUT parameter will be the
limited output.
The transducer block is connected through a
channel to the AO block. Through this channel the
OUT value and SP are transceived.
In order to set the AO block to AUTO, the TB and
the RB have to be in AUTO. Further, the AO block
has to be scheduled. Using a fieldbus configura-
tor from, for example, National Instruments or
Honeywell, scheduling can be done by adding the
unit to a project and then clicking on the "upload
to device" icon.
To write a setpoint value by hand, add Man to
MODE->Permitted parameter, and then choose
MODE->Target to Man. Make sure that the unit
is scheduled.
Example
A typical FF block loop control might look like the
following:
Where the positioner is represented by the AO-
block.
22
FCD PMENIM0001-06 A5 09/16