Det-Tronics EA2100CG Eagle 2000 Communication Gateway - Manual (Page 12)

DESCRIPTION
The DCU is available in three different configurations to
accommodate a variety of gas sensing devices.
– The combustible gas DCU (EA2200DCU EX)
includes a transmitter board for converting the sen-
sor output signal (in millivolts) to a 4 to 20 ma signal
for input to the communication module board. The
transmitter board is furnished with the test points
and controls needed for calibrating the sensor.
– The universal DCU (EA2200DCU UNIV) contains a
communication module PC board and a terminal
wiring board. This DCU is used with oxygen and
toxic gas sensors.
– The intrinsically safe DCU (EA2200DCU IS) is similar to
the universal DCU, but includes an intrinsically safe bar-
rier board in addition to the other PC boards. This DCU
model is required for use with intrinsically safe sensors.
ENCLOSURE
The explosion-proof, watertight aluminum enclosure is
designed for use in Class I, Division 1, Groups B, C and
D hazardous locations. It is designed to meet CEN-
ELEC requirements for EEx d IIC T5 hazardous loca-
tions, and is IP66 and NEMA 4 rated. The removable
cover is furnished with a window to allow the operator to
view the three status indicator LEDs on the communica-
tion module PC board.
The enclosure is furnished with two 3/4 inch NPT con-
duit entries.
DCU CIRCUIT BOARDS
Terminal Wiring Board
All external wiring is connected to screw terminal con-
nectors on the terminal wiring board located inside the
junction box.
Communication Module Board
The communication module consists of a printed circuit
board containing the communication circuitry. The com-
munication module PC board used in the DCU is identi-
cal to the PC board used in the EA2300CM Eagle
Communication Module.
The communication module provides communication
capability for the sensor/transmitter by converting the 4 to
20 ma transmitter output to a 10 bit digital signal and trans-
mitting the value as a process variable to the gateway. It
can also accept two digital (contact) inputs. In addition,
the communication module sends status and diagnostic
information for itself and its sensor to the gateway.
Refer to Section II of this manual for a complete descrip-
tion of the communication module board.
Transmitter Board
DCUs that are used with combustible gas sensors
(EA2200DCU EX) incorporate a transmitter board. This
board furnishes operating power for the sensor and con-
verts the sensor output to a 4 to 20 ma signal for input to
the communication module board. The transmitter also
provides zero and span potentiometers for calibration of
the sensor. The DCU is calibrated using the Eagle sys-
tem calibration algorithm C (algorithm D for oxygen sen-
sors), as described in the “Calibration” section.
I.S. Barrier Board
Intrinsically safe sensors must be powered through an
I.S. barrier, which is included with model EA2200DCU IS.
8
6.5
(16.5)
3.38 (8.4)
4.1 (10.4)
B1520
4.5 (11.4)
4.1
(10.4)
3/4" NPT (2)
0.3 DIA.
(0.8)
Figure 8—Dimensions of DCU and Network Extender Enclosure
in Inches (Centimeters)