Design and Implementation of HC900 Control System - Allowable Function Blocks for Process and Safety Functions
20 HC900 Process & Safety Controller Safety Manual Revision 1.9
01/14
3 Position Step
This block combines a PID controller with 3 Position
Step Control output functions to provide motor
position control without position sensing. Allows the
control of a valve or other actuator having an electric
motor driven by two digital output channels; one to
move the motor upscale, the other to move it
downscale, without a feedback slidewire linked to the
motor shaft. Outputs 17 through 32 of the 32
Channel DO Module, may not be used for TPO (Time
Proportioning Output), PPO (Position Proportioning
Output) or TPSC (Three Position Step Output) output
types.
X
Write Tune Const
Writes the numerical value of Gain, Rate, and Reset
to a Target PID, TPSC, or CARB block without any
operator interaction. Invalid for block number whose
type is other than PID, CARB, or TPSC. If the target
block is in AUTO mode, tuning parameter change will
cause a bump in the output. If any input value is "out-
of-range", no values will be written. Error checking
must be added to the Designer configuration.
X
Auto Manual Bias
On transfer from Manual to Auto; Bias is calculated to
make PV + Bias = Output.
X
Setpoint
Programmer
Blocks
Programmer
Runs a setpoint ramp/soak program that produces a
setpoint output on a time-based profile that is loaded
into the block. A single profile may be from 2 to 50
segments in length. Profiles are stored in the
controller’s memory. Each segment of the profile may
be a ramp or soak except the last segment must be a
soak. In addition to the main ramp and soak output
value, a second (AUX) analog value is available for
each step of the program. This output is a fixed soak
value that may be used to provide a setpoint value for
a secondary control loop in the process. A Setpoint
guarantee function is provided that holds the program
if a process variable exceeds a predefined deviation
from setpoint. Selections allow setpoint guarantee to
be active for the entire program, for soak segments
only, or for user specified segments, or for no
segments. Up to 3 Process Variables may be
configured as inputs to the block for setpoint
guarantee.
X
Recipe Selection
Block
Loads numbered RECIPE (NUM) when digital signal
(LD) is ON into the various blocks of the controller. If
LD = ON, then: Recipe numbered (NUM) is loaded in
place of the current set of variable values.
X
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