A8814 Acq
Page 11
Connecting Third Party Modbus Devices
Step 4
(optional) - Connect the Modbus network loop as shown in the wiring diagram. Follow the
manufacturer’s instructions for installing and powering the Modbus devices. Verify that the Modbus address
settings are unique for each device (i.e., no two devices with the same address) and power up the device.
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
www.obvius.com
Low Voltage analog, pulse, and RS485 wiring that enters electrical panels must have a minimum insulation rating
that exceeds the voltage inside the panel. In addition, other regulations may apply; consult the building codes in
your area prior to installation.
The RS485 port on the A8814 has a built in terminator. A 150 ohm termination resistor should be placed at the
other end of the RS485 loop, between the + and – wires. For more information about RS485 termination, read
the Modbus FAQ at www.obvius.com
Some Modbus devices do not use the same label notation as the AcquiSuite. Rather than +,-,S, Emon uses Low,
High, and Gnd. To attach an Emon meter, use + to high, - to low, and shield to gnd.
The AcquiSuite A8814 built in electrical meter uses Modbus address 250, and will show up in the Modbus device
count as a single Modbus device. Additional meters and sensors can be added to the Modbus loop.
Laptop/Computer Setup
Step 1
- You must have a computer to access and configure the AcquiSuite. This computer must have an ethernet
connection (on the LAN or by direct connection) and must have a web browser installed such as Internet
Explorer or Netscape.
Note: If your building already has an existing LAN that the AcquiSuite is attached to, you can use an existing
computer on that LAN. Check with your network administrator for details. If this option is available, use a LAN
connected computer and skip to the “AcquiSuite administration overview” section below.
