Design and Implementation of HC900 Control System - Allowable Function Blocks for Process and Safety Functions
Revision 1.9 HC900 Process & Safety Controller Safety Manual 23
01/14
Toggle Flip-Flop
Provides an ON state output when a digital input goes
from OFF to ON and the previous state of the output
was OFF, and an OFF state output when the digital
input goes from OFF to ON and the previous state of
the output was ON. OUT = ON when X changes from
OFF to ON and the previous state of OUT was OFF.
OUT = OFF when X changes from OFF to ON and
the previous state of OUT was ON. Reset sets output
to OFF, regardless of current state.
X
X
Free Form Logic
Reads digital inputs A through H and calculates the
output based on specified Boolean logic function.
Offers the following Boolean logic functions:
AND entered as *;
OR entered as +;
NOT entered as not;
XOR entered as ^;
( - Left parenthesis;
) - Right parenthesis.
This function block consumes significantly more
execution time than gate logic. Extensive use of this
block in the fast logic scan can add significantly more
time to the overall system cycle time.
Use only the following list of words and characters in
an equation:
AND - logical AND;
OR - logical OR;
NOT - unary NOT;
XOR - exclusive OR,
or "( )", "[ ]", And "{ }" parentheses - three types.
Variables cannot have "No Type". A left parenthesis
must have a matching right parenthesis. The
matching parenthesis must be the same type, that is,
"( )", "[ ]", or "{ }". Parentheses may be nested to any
depth. Logical AND, OR, and XOR must have a left
and right operand. Unary NOT must have one
operand to the right, and the operand must be
enclosed in parentheses; for example, NOT (g).
X
X
Pushbutton
Provides the interface from the operator panel to the
logic functions of the controller. Provides a one-shot
logic ON in response to pressing the corresponding
function key on the operator interface. This selection
lets you configure the Pushbutton function display,
which will provide the interface to the four logic
operator keypad keys (F1 through F4). You can do
this for up to 8 Pushbutton blocks giving you 4 groups
(total 32 pushbuttons) that can be set up for selection
on your display buttons (1-8). When you select a
pushbutton group on a display button (1-8), the
operator interface will display the pushbutton function
group screen and buttons F1-F4 on the operator
interface will display the information that has been set
up for that group. Note: This was an original standard
display page in the 559/1042 Operator Interfaces.
This function block can be retained when converting
to the 900CS Control Station by adding independent
Pushbuttons in the Station Designer software and
include feedback for each.
X
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