Power and Communication Connections
Hardware Installation
Step 1
- Unpack materials: Remove all materials from shipping box and verify all required components are available
Step 2
- Mount the A90DC-12 inside the electrical enclosure. Be sure to provide enough room to route the load wires
through the hall effect sensor openings.
Step 3
– Attach the power supply to the A90DC-12. Be sure to observe the polarity. Note: Power can be
disconnected by removing the screw terminal plug from the A90DC-12 power connection socket.
The A90DC-12 can operate on
Step 4
- Connect the RS485 Modbus network loop as shown in the wiring diagram. Follow the manufacturer’s instructions
for installing and powering the Modbus Master device. Verify that the Modbus address settings are unique for each device
(i.e., no two devices with the same address). Connect each device in the chain by “daisy-chaining” the devices together .
O and - polarity on the Modbus devices. For more information about Modbus loops, please read our Modbus FAQ
available at
Do not ground the RS485 shield inside the electrical panel. All RS485 and 24vdc power wires, including the shield should
be insulated to prevent accidental contact to high voltage conductors.
The RS485 and 24vdc power cable should be mechanically secured where it enters the electrical panel.
The wire used to provide RS485 communications should be insulated to meet requirements of the voltages present inside the
box that the A90DC-12 is mounted within. For example, Belden 1120A has a 600v insulation rating and can be used in
many applications. Check with your electrical installer for details as local code requirements may vary.
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A90DC-12 – DC Current Monitor
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