Owner's manual

FOUNDATION
TM
Fieldbus Blocks Manual
A-8
Compensation inputs which are not configured are not used in the
calculation. PV is always used.
• Fourth-Order Polynomial
• Simple HTG Compensate Level
If there is a divide by zero and the numerator is positive, function will
be limited to COMP_HI; if the numerator is negative, function will be
limited to COMP_LO.
DISCRETE INPUT (DI)
FUNCTION BLOCK
The configuration of the DI function block and its associated output
channels depends on the specific application. A typical configuration for
the Discrete Input involves the following attribute:
IO_OPTS Select Invert to reverse the value supplied for
a two-state input.
Application Example:
Discrete Input Function Block
Situation
A DI block is used with a DO block to drive a solenoid valve under the
active condition.
Solution
The configuration differs depending on whether the valve actuator is
designed to open or close under the active condition, or to fail open on
the loss of power. Table A-8 lists the appropriate settings for each
attribute, and Figure A-7 illustrates the correct function block
configuration.
TABLE A-8. Analog Output Function
Block Configuration Example
Figure A-7. Discrete Input Function
Block Diagram Example
func PV t(1)
2
t(2)
3
t(3)
4
+++=
func
PV t(1)–
PV t(2)–
-----------------------=
Configuration
Setting
Open if Active Close if Active
IO_OPTS Invert Not selected Selected
fieldbus-fbus_11a
Input
Output
DI
Function
Block
DO
Function
Block
OUT_D