Det-Tronics EA2100CG Eagle 2000 Communication Gateway - Manual (Page 10)

OUTPUTS
A 5 ampere SPDT relay is provided. When the commu-
nication module is used with a U8700 or U8800, the
relay output is used to reset the transmitter. The relay is
actuated for 1 second when a “reset sensor” signal is
sent to the communication module by the gateway in
response to a request from the host.
If the communication module is used with a different
sensor/transmitter, the relay is activated when the “alarm
1” threshold is reached. The communication module
alarm relay is latching and is reset by a command from
the host through the gateway or by cycling power.
The alarm relay is reset by setting the reset sensor bit in
the communication module control word. If the process
variable is still above the alarm threshold, the relay will
not be reset.
INPUTS
The communication module has one 4 to 20 ma non-iso-
lated input, with an input impedance of 200 ohms in
series with a protection diode. A 10 bit analog-to-digital
(A/D) converter digitizes the analog signal.
In addition to the 4 to 20 ma analog input, the communica-
tion module has two digital inputs. Depending on the type
of detector being used, digital input 1 is dedicated to either
detector calibration or detector fault indication. (Refer to
the System Configuration Matrix, form number 95-8453, to
determine the function of input 1 for a specific detector.)
When the communication module is used with a U8700
or U8800 Transmitter, the first digital input is connected
to the transmitter calibration relay contacts. The trans-
mitter then uses this relay to signal calibration informa-
tion to the communication module.
The second digital input is typically used as a simple
switch input. The status of this input is reflected in the
communication module status word. This input can be
configured as a normal or inverted input.
REED SWITCH
A reed switch, located on the terminal board, enables
calibration of the sensor without opening the enclosure.
The switch is activated by placing a magnetic calibra-
tion tool on a specified location on the side of the enclo-
sure (midway between the two mounting holes, about an
inch from the mounting surface).
EVENT LOGGING
The communication module is capable of logging up to
8 calibration events and 8 alarm events. Date and time
stamping of these events is also provided.
Calibration Log
A log is kept for each calibration. This information can
be used by the operator to evaluate the remaining life of
a sensor. An aborted calibration is indicated by zeros in
the zero and span values. The calibration log is cleared
when the sensor replacement switch is pressed and the
calibration is successfully completed.
The initial calibration is logged in position one, where it
remains for the life of the sensor. If more than 8 calibra-
tions are performed without the sensor replacement
switch being pressed, the newest calibration data will
replace the second oldest so that the initial calibration
data can be saved. The old calibration data will be lost.
This feature enables sensor sensitivity trending to aid in
maintenance or troubleshooting.
Alarm Log
A log of alarm 1 and alarm 2 events is stored in each
communication module. Time, date and alarm type are
logged for each alarm event. A maximum of 8 events
can be stored. If more than 8 events are logged, the
oldest event will be overwritten.
FAULT TOLERANT NETWORK
The Eagle system utilizes a unique technique for detect-
ing an open or short in the network wiring. The commu-
nication module contains both the software and hard-
ware necessary to isolate it in the event of a wiring fault.
This allows communication to continue in the remainder
of the network utilizing the second network communica-
tion port of the gateway. Refer to “Network Operation
During a Fault Condition” in Section I for complete infor-
mation.
ENCLOSURE
The explosion-proof, watertight aluminum enclosure is
designed for use in Class I, Division 1, Groups B, C and
D hazardous locations.
The enclosure is furnished with two 3/4 inch NPT con-
duit entries.
TERMINAL WIRING BOARD
All external wiring is connected to screw terminal con-
nectors on the terminal wiring board located inside the
junction box (Figure 7). The communication module cir-
cuit board connects to the terminal wiring board with a
ribbon connector and is mounted inside the junction
box above the terminal wiring board.
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