Honeywell HC900 - Ethernet Devices;Considerations

Design and Implementation of HC900 Control System - Allowable Function Blocks for Process and Safety Functions
Revision 1.9 HC900 Process & Safety Controller Safety Manual 31
01/14
Force Present
Output indicates the presence of any forced blocks in
the controller. Input can clear all forces and prevent
new forces.
X
Redundancy
Status
Used with redundant CPUs only, such as C75S. The
output pins indicate the lead/reserve status of CPU A
and CPU B. The input can force a failover between
CPUs.
.
X
X
Four Alarm with
Hysteresis
This block monitors four analog input values (SP1,
SP2, SP3, SP4) and performs up to four alarm
comparisons against the PV input. Configurable
Alarm types are Disabled, Low, High. The associated
output pins, AL1 through AL4, will turn ON if the
configured HIGH or LOW alarm condition is present.
The individual hysteresis settings for each alarm are
used to prevent output cycling.
X
X
Fault Monitor
This block monitors a user selected fault condition of
the Controller, Rack or Module allowing the user to
configure their fault stategy. Multiple types of faults
can be monitored with multiple fault monitor blocks.
X
X
Signal Selector
Blocks
High Selector
Selects higher of two analog input values (X & Y) for
output. Indicates when Y is higher than X. If X > or =
Y, then: OUT = X; YHI = OFF. If X < Y, then: OUT =
Y; YHI = ON.
X
X
Low Selector
Selects lower of two analog input values (X & Y) for
output. Indicates when Y is lower than X. If X < or =
Y, then: OUT = X; YLO = OFF. If X > Y, then: OUT =
Y; YLO = ON.
X
X
Switch
Selects input Y for output when digital input signal
(SY) is ON. If SY = ON, then; OUT = Y. Otherwise,
OUT = X.
X
X
Rotary Switch
The single output value is selected from up to 8
analog inputs by a number from 1 to 8. Note:
Numbers less than one select input one as the
output. Numbers greater than eight select Input 8 as
the output.
X
X
Bumpless Analog
Xfer Switch
Provide "bumpless" switching between two analog
input values (X, Y) that is triggered by a digital input
signal (*SY). When switched, the output ramps to the
new value at a specified rate. YRATE and XRATE
configuration values set the rate at which the output
(OUT) changes to a switched value (Y or X),
respectively. If SY is switched to ON, then: OUT
changes to Y value at YRATE. If SY is switched to
OFF, then: OUT changes to X value at XRATE. When
OUT reaches the selected target input, OUT tracks
the selected input (until SY changes).
X
X