Design and Implementation of HC900 Control System - Allowable Function Blocks for Process and Safety Functions
26 HC900 Process & Safety Controller Safety Manual Revision 1.9
01/14
On-Delay Timer
Provides an ON state logic output delayed by a user
specified delay time after an OFF to ON transition of
the RUN input. An ON to OFF transition of the RUN
input before the delay time has elapsed causes the
timer to reset. Transitions from ON to OFF of the
input are not delayed. If RUN is OFF, then OUT =
OFF. If previous RUN input is OFF and RUN is ON,
then TIMER = DELAY. If RUN is ON and TIMER is 0,
then OUT = ON (delay time has timed out). If RUN is
ON and TIMER is NOT 0, then Time = TIMER–1.
X
X
On Delay / Off
Delay Timer
Block is configurable as On Delay or Off Delay. For
On Delay, output turns ON when timer expires. For
Off Delay, output turns OFF when timer expires.
X
X
Calendar Event
The Calendar Event Block compares user-entered
time-and-date setpoints to the real-time clock to
generate digital Event outputs. These Event outputs
can be integrated into a control strategy to activate
time-synchronized activities. For example, the Event
outputs can be used turn-on or turn-off the lights in an
office building. Each Calendar Event block supports
up to eight Event outputs. In addition, the block allows
you to configure up to five sets of time-and-date
setpoints, called Setpoint Groups. These Setpoint
Groups can be used to activate different sets of time-
and-date setpoints to handle different conditions.
Using the example of an office building, Setpoint
Groups can be used to activate a different set of time-
and-date setpoints for each season of the year
(Spring, Summer, Fall, and Winter). Each Calendar
Event block supports five Setpoint Groups. The block
also allows you to configure up to 16 Special Days.
On these Special Days the Calendar Event Block will
override its normal Event processing for a 24-hour
period. For example, you can configure selected
Event outputs to remain off on designated holidays.
X
Real Time Clock
The Real Time Clock block provides output pins that
you can access in your configuration to make
decisions based on the value of the controller’s Real
Time Clock value.
X
Time and Date
Controls change between Daylight Saving and
Standard time. Indicates when controller time is in
Daylight Saving. If the controller is using a network
time server, indicates if the connection to server has
failed.
X
Math Blocks
Scale and Bias
Multiplies an analog input value (X) by a scaling
constant (K) and adds Bias to it.
X
X
ADD
Adds two inputs (X, Y) to get an output.
X
X
SUB
Subtracts one input (X) from another (Y) to obtain an
output.
X
X
MUL
Multiplies one analog input value (X) by another (Y).
X
X
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