Det-Tronics EA2100CG Eagle 2000 Communication Gateway - Manual (Page 16)

of the gateway and set the fault bit in the gateway status
word in the event of a problem. A watchdog timer
resets the gateway if its software gets caught in a loop.
In the second form of diagnostics, the gateway provides
a watchdog timer for each configured device on the
loop. Each time the device reports to the gateway, the
timer accumulator is reset to zero and the timer starts
over. If a device does not respond before its watchdog
timer expires, the gateway sets the “not communicating”
bit in the status word for that device.
CAUTION
The fault detection circuitry does not monitor the
operation of external response equipment or the
wiring to these devices. It is important that these
devices be checked periodically to ensure that
they are operational.
FAULT TOLERANT COMMUNICATION
Fault tolerance is provided by constructing the communi-
cation network as a loop starting and ending at a pair of
communication ports on the gateway. Communication
between the gateway and the communication modules
on the network normally occurs through the first port. If a
fault occurs somewhere in the network wiring, the gate-
way annunciates the fault, while fault isolation circuitry in
the communication modules isolates the problem section
of the network. Communication is re-established
between the gateway and the communication modules
downstream of the problem from the other direction utiliz-
ing the second network communication port. This fea-
ture minimizes the possibility of a communication break-
down in the event of a wiring fault in the communication
loop. Refer to “Network Operation During a Fault
Condition” in Section I for additional information.
SYSTEM CAPACITY
The gateway can support a communication network
consisting of up to 60 detectors in a 2000 meter wiring
loop. By adding network extenders to the loop, it can
be expanded by up to 60 detectors and 2000 meters of
wiring per extender, up to a maximum of 250 nodes.
To further expand the system, gateway multiplexing is
possible, as illustrated in Figure 11.
Refer to the “Network Extender” section of this manual
as well as the network extender instruction manual (form
95-8430) for complete information.
INSTALLATION
The Eagle Communication Gateway is rack mountable
and occupies two spaces in a standard Det-Tronics
Q4004 Mounting Rack (in a non-hazardous area).
Section V
EA2400NE
Network Extender
APPLICATION
The EA2400NE Network Extender expands the capabili-
ties of the Eagle system by allowing additional nodes as
well as additional wiring to be added to the communica-
tion loop. Without a network extender, the communica-
tion network is limited to 60 nodes on a 2000 meter
loop. Each network extender, however, increases the
capacity of the loop by up to 60 nodes and 2000 meters
of wiring, up to a maximum of 250 nodes and 10,000
meters of wiring.
The electronic circuitry is mounted inside an explosion-
proof metal housing for installation in hazardous locations.
FEATURES
• Increases capacity of total network
• Screw terminal connectors
• Transformer isolation protection.
SPECIFICATIONS
INPUT VOLTAGE—
18 to 29 vdc.
POWER CONSUMPTION—
2 watts nominal at 24 vdc, 5 watts maximum.
INPUTS/OUTPUTS—
Digital, transformer isolated (78.5 kbps).
TEMPERATURE RANGE—
Storage: –49°F to +185°F (–45°C to +85°C).
Operating: Refer to the “System Capacity” section
(under General Application Information)
for temperature limitations.
12
A1543
GATEWAY GATEWAY GATEWAY
MULTIPLEXER
HOST
Figure 11—Gateway Multiplexing