Connect the Ethernet/Modbus Cables
Front View of the PDU
- Open the middle front door.
- When a temporary Ethernet connection is needed: Connect an Ethernet cable with RJ45 plug to the Ethernet port. This is a temporary connection which requires that the middle front door is open.
- When a temporary Modbus connection is needed: Connect
the Modbus cable with RJ45 plug to the Modbus port on the PDU. This
is a temporary connection which requires that the middle front door
is open.
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2-wire or 4-wire shielded twisted pair cables must be used for Modbus connections. Use a cable for Modbus serial link (RJ45 to RJ45 or RJ45 to free wires depending on the Modbus controller characteristics).
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The Modbus port is optically isolated. The Modbus port’s ground is not connected to any other ground.
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Install 150 Ohm termination resistors at each end of each bus if the buses are very long and operate at high data rates. Busses under 610 meters (2000 feet) at 9600 baud or under 305 meters (1000 feet) at 19.200 baud should not require termination resistors.
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Install 400-650 Ohm bias resistors at or inside the system controller: One from D0 to ground and one from D1 to +5 VDC.
Example: Modbus 4-Wire on RJ45 Connector
If more than one PDU must be connected to the Modbus controller, use an RJ45 Modbus hub or splitter block.
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- When a permanent Ethernet/Modbus connection is needed: Perform one of the following:
- Connect the Ethernet cable with RJ45 plug to the extension port on top of the PDU. By default the extension cable is connected to the Ethernet port. OR
- Connect the Modbus cable with RJ45 plug to the extension port on top of the PDU. By default the extension cable is connected to the Ethernet port – move the extension cable to the Modbus port.