ICS Regent
®
PD-6032
Fire Detector Input Modules
(T3419)
Issue 1,
Fire detector input modules provide interface
detector inputs such as smoke detectors, flame detectors,
temperature detectors, and manual alarm call points. Each
module performs line monitoring on the field wiring
connections and automatic testing of the module’s input
electronics. Input and line status are reported back to the
controller for use in application program logic.
s for 16 fire
March, 06
Features
·
Sixteen input points.
·
Individual channel Reset control output to reset latched fire
detectors.
·
Fault tolerant operation when redundant modules and sensors
are configured.
·
Hot-replaceable.
•
Complete, automatic testing of all input circuits.
•
Automatic line monitoring detects open and short field wiring
faults.
·
Individual front panel indicators on each module show the
module’s fault/active and power st
indicators for each point.
·
2500 volt minimum electrical isolation between field and logic
circuits.
·
TÜV certified, Risk Class 5.
The input module circuits are thoroughly tested, providing a
fail-safe interface for safety critical inputs. For fault tolerant
configurations, two fire detector input modules are used to
atus, as well as input status
Industrial Control Services
1
Fire Detector Input Modules
connect to redundant field sensors. In this dual module
configuration, a failed module can be removed and replaced
without affecting system operation.
The module requires connection to a field power supply
voltage, ranging from 15 to 40 VDC. This supply voltage is
internally regulated to power the fire detector field input
circuits.
(T3419)
Module Operation
A block diagram of a typical fire detector input module is
shown in Figure 1.
2
Figure 1. Block Diagram of Fire Detector Input Module.
A field power supply is connected to the fire detector input
module. The field power is internally regulated to 23.5 Vdc to
power the fire detector field inputs. Each input is biased to
Industrial Control Services
Fire Detector Input Modules
(T3419)
this regulated voltage with an internal resistor. Externally
each input connects to an associated field sensor and a line
terminator. The module monitors the input voltage to detect
a variety of input states. The module can discriminate and
report sensor tripped, sensor healthy, line open and line
shorted conditions. Additional circuits allow the mo
dule to
reset a latched fire detector by removing power from the
associated input circuit.
Internally the module generates a reference voltage that is
compared to the field inputs. The comparator generates an on
or off state depending on which voltage is greater. The field
side FPGA controls and monitors the reference voltage signal
and reads the status of all 16 input comparators. This
information is stored and sent through optical isolation to the
logic-side FPGA. This FPGA interfaces the input date
I/O safetybus and drives the module’s front panel indicators.
to the
Testing and Diagnostics
Standard I/O Module Testing
The processor modules send triplicated read data requests to
the input module over the I/O Safetybus. The processors’
addressing data and data read requests are voted by the
module (preventing I/O Safetybus failures upstream from the
module from affecting its ability to be read). The voted result
is then passed to the I/O bus interface logic.
After receiving the voted data read requ
est, the I/O bus
interface logic sends its input data to the module’s three bus
drivers. Each of the three bus drivers is independently
controlled — preventing failures in a single driver from being
propagated into the rest of the system.
The bus drivers then move the data onto the I/O Safetybus
which, in turn, passes it to the processors.
Each module’s voter circuits are periodically tested by the
processor modules. Discrepant data are sent through one of
three legs of the I/O Safetybus to determine wh
ether the
module’s voter is able to outvote the incorrect data. A failure
to return the correct majority-voted result to the processors
produces an I/O module error indication at the processor
modules and a module fault indication at the I/O module.
PD-6032
Mar-06
3
Fire Detector Input Modules
Each type of module has a unique identification code that is
read by the controller. This code lets the controller know
which type of module is installed in each I/O chassis slot and
address that module and its points specifically. The processor
modules peri
to determine whether the type of module installed matches
type of module indicated in the I/O configuration that was
loaded when the system was started. If a module is removed,
or is replaced with a module of a different type, the processor
modules will indicate I/O module errors.
Loopback logic tests periodically write data to the module and
then read it back to determine whether the module’s I/O bus
interface logic is functioning correctly.
(T3419)
odically check each module’s identification code
Input Circuit
Testing
The field interface circuits of the fire detector input module
are completely tested to detect stuck-on or stuck-off input
circuit faults and identify input wiring open and short circuits.
The automatic execution and evaluation of the input testing
is controlled by the triplicated Regent processor modules.
During normal operations, the internal reference voltage is
set to three levels and the comparator output is read. These
three reference voltage levels represent thresholds that
determine whe
ther the input signal is in alarm or healthy and
if the field wiring is open circuit or short circuit. The logic-side
FPGA determines input status and line fault status based on
the comparator data for the three voltage levels. The FPGA
data is provided to the I/O processors for application
processing.
On a background basis, the I/O processors test the input
circuit comparators and logic circuits for stuck-on and stuck
off failure modes. During testing the D/A converter generates
two reference voltages
outside the normal operating range of
the field input voltages to test that the comparator output can
turn-off and turn-on. The I/O processors read the resulting
input status, line fault status, and reference voltage readings
for the test cycle to determine if there are faults in the input
circuits or the common data paths.
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Industrial Control Services
Fire Detector Input Modules
Note:
(T3419)
If the I/O processors detect a faulted input circuit, an I/O
module fault is indicated at the processor modules and the
Fault LED on the face of the input module is turned on.
Input C
ircuit Test Interval
The Regent processor modules schedule testing of the input
circuits on a background basis. The test interval for these
circuits may range from a few seconds to several minutes,
depending on the application program scan time and the size
of the I/O configuration. The equation below can be used to
estimate the test interval for monitored digital inputs.
TI = 172 * IOU
where:
TI
IOU
TSCAN
=
=
QTY
= T
* TSCAN + 2
QTY
Test interval, seconds
Quantity of I/O Units in the system (1 to 16)
he application program scan time, seconds
For example, for a system with 8 I/O units and an application
scan time of 60 milliseconds, the test interval would be:
TI = 172 * IOU
TI = 84.6 seconds
* TSCAN + 2 = 172 * 8 * 0.060 + 2
QTY
In this system, all of the fire detector input modules would be
tested for stuck-on and stuck-off faults approximately every 85
seconds. This test interval can be used in reliability and
availability calculations to select the fault tolerant input
configuration that meet the application’s safety requirements.
PD-6032
Mar-06
Due to I/O processor fault filtering algorithms, it may take up
to four test intervals to report a failed input module as a
permanent fault
Front Panel Indicators
Figure 2 shows the physical features of the fire detector input
modules. The front panel of each module contains fault/active
and power indicators for the module as well as input status
indicators for each channel.
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Fire Detector Input Modules
(T3419)
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Figure 2. Fire Detector Input Module.
Industrial Control Services
Fire Detector Input Modules
(T3419)
Active/Fault Status Indicator
This green and red LED pair indicates the overall health of
the module and its field circuits. During normal operation the
green ACTIVE indicator flashes at the controller's scan rate.
If a module fault occurs the red FAULT indicator switches on
and the green indicator switches off.
Power Status Indicator
The POWER GOOD LED indicates the presence of field
voltage at the module’s field power input terminals and the
overall health of the module’s field power regulator circuits.
Input Status Indicators
Input status indicators show Fault and Alarm status for each
point.
A red ALARM status indicator turns on when the fire detector
input is in the tripped alarm state. The indicator is also on if
the input signal is shorted.
A yellow FAULT indicator turns on when the input circuit is
open or short circuit.
Application
Simplex Configuration
Fire detector input modules provide a suitable interface to
safety-critical input signals.
Fir
e detector input modules provide a suitable interface to
safety-critical input signals. The circuits in the input modules
are automatically tested and annunciated, providing a fail
safe interface to digital inputs.
Fault Tolerant Connection
For critical inputs, redundant input modules are used with
redundant input sensors in a fault tolerant configuration. In
this configuration each input module is connected to one of
two redundant sensors in the field. With this configuration, if
a fault occurs on one module or sensor, it can be removed and
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PD-6032
Mar-06
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