Manual

1600A-N1R

1600A-N1R Instruction Manual Rev. 0.1 Page 8 of 38

3.2 Connecting to the I/O Modules

4-20mA Gas Sensors

Connect 4-20mA type gas sensors to the Model DA4 4-20mA input modules. There are four 4-20mA inputs

in each Model DA4 module.

4-20mA

INPUT

COMM

Typical Sensors

Sensor 2

Sensor 1

Sensor 3

Sensor 4

Figure 9 Model DA-4 and 4-20mA Gas Sensors

RS-485 Modbus Gas Sensors

Connect the five wires from the Modbus™ gas sensors (Detcon Model 600 and Model 700 Series types) to the

din rail mounted terminals labeled RS-485 “A”, “B”, and “Shld” and VDC “+” and “-”. Note: the controller

power supply is only capable of handling 3-3.5Amps accumulative. If the external sensors plus the

controller’s internal modules exceeds this rating, only three wires (RS-485 “A”, “B”, and “Shld”) should be

used and a remote DC power source should be utilized to provide DC power for the remote mounted gas

sensors.

NOTE: A 120: end of line resistor should be installed on the last gas sensor in the serial loop to enhance

communications reliability.

Figure 10 Modbus™ Gas Sensor Connections