Operator Manual
Page
5
of
40
P/N 1580281
SEC3120 Digital Transmitter
Sensor Electronics Corporation
Rev 10, 20150707
-40
to +40°C (-40 to +104
F) when equipped with the optional LCD heater
0° to +40°C (32° to +104°F) when not equipped with the LCD heater.
The unit will operate below this temperature, but at a reduced function, specifically the LCD may
become illegible or damaged.
0 to 99% RH (non-condensing)
Altitude / Elevation:
IEC 61010-1 certified to 2000 meters.
Mechanical:
Construction:
Epoxy Coated Aluminum
Dimensions: (See drawing 3120-XXX for details)
Height: 5 Inches (128 mm)
Width: 5 inches (128 mm)
Depth: 4.8 inches (122 mm)
Weight: 4.55 lbs (2.0 kg)
Conduit Entry:
Three (3) 3/4 inch NPT
For hazardous location installations seals must be installed within 18 inches of
conduit entries.
Electrical:
Mains Supply (Operating Voltage):
24 VDC Nominal (Range: 18 to 32 Vdc) measured at the detector head
Current Draw: (without sensors)
Average: 250 mA (Peak: 500 mA)
Input, Sensor (Digital):
0-5 V, Sensor Electronics Corp. (SEC) Proprietary, Single-Wire, Digital signal from the sensor.
This signal is used by the sensor to communicate status and gas data and is used by the display to
initiate sensor calibration and query status.
Output (Analog):
4-20 mA (Source Type), max 1000 ohm load at 24 Vdc supply voltage.
The 4-20 mA output is provided by the sensor and is passed through the SEC3120 display. The
display can be located at any point in the sensor’s output loop. Consult the appropriate sensor
manual for 4-20 installation requirements.
Output (Digital):
RS485 LAN (isolated) MODBUS RTU Slave, compatible with Modicon Modbus Specification PI-
MBUS-300 Rev. J. Refer to SEC Modbus Technical Sheet (SEC P/N 1580282) for specific
configuration and use information.
Output (Relays):
Three (3) Alarms: Low, Mid High. One (1) Fault
Rated for 8 Amps, 30 VDC or 120VAC