Mitsubishi Electric MelcoREMOTE, Installation And Operation Manual

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Depending upon the application and the equipment connected to MelcoREMOTE, termination and/or pull up/down
resistors may be required. MelcoREMOTE has built in jumper selectable termination and pull up/down resistors.
To power RS-485 Modbus devices which require 24VDC, MelcoREMOTE can be used to provide DC power and
ground from the
RS-485 + and RS-485 - connections respectively. Ensure the current draw of the devices does not
result in the power supply exceeding its maximum current rating (See the Technical specification section for more
information).
If an external power source is used to power the device, ensure that MelcoREMOTE and the device have a shared
ground connection (the
RS-485 - terminal can be used for this).
For help with RS-485 connectivity see the
Troubleshooting section.
10.2. Modbus TCP devices
MelcoREMOTE has an Ethernet port which can be used to communicate with external devices which support the
Modbus TCP communication protocol.
A
crossover Ethernet cable can be used to form a direct connection between MelcoREMOTE and a single Modbus
TCP device. If multiple devices are to be connected then a network must be created using one or more Ethernet
switches/hubs, along with
straight through Ethernet cable. This is the same as how Centralised Controllers connect to
MelcoREMOTE.
10.3. Modbus Slave mode
Either one or both of the two RS-485 ports on MelcoREMOTE can be configured to provide Modbus Slave functionality.
This allows MelcoREMOTE to act as a Modbus Slave device so that 3
rd
party controllers can access all I/O data from
the MelcoREMOTE.
The
Modbus Slave Register tables sections provides more information on Modbus Slave mode.
MelcoREMOTE can also be configured to also act as a Modbus TCP Slave device.
10.4. I/O Module Mode
MelcoREMOTE can be set to be a standalone I/O module which does not require a server connection. MelcoREMOTE
then acts as a Modbus RTU Slave and Modbus TCP Slave device to allow its I/O data to be accessed.
See the
Configuration and Commissioning section for more information.