9.1 Overview on RS-485 Communication
9-1
Chapter 9 RUNNING THROUGH RS-485 COMMUNICATION
9.1 Overview on RS-485 Communication
The FRENIC-MEGA has two RS-485 communications ports at the locations shown below.
(1) Communications port 1: RJ-45 connector for the keypad (Modular jack)
(2) Communications port 2: RS-485 terminals (Control circuit terminals SD, DX-, and DX+)
COM port 1 COM port 2
Using the RS-485 communications ports shown above enables the extended functions listed below.
• Remote operation from a keypad at the remote location (COM port 1)
Using an extension cable to connect the standard keypad to the RJ-45 port allows you to mount the
keypad on a panel located far from the inverter, enabling remote operation. The maximum length of the
extension cable is 20 m.
• Operation by FRENIC Loader (COM port 1)
A Windows-based PC can be connected to the RJ-45 connector (RS-485 communication) or the USB
port on the standard keypad. Through the interface, you can run FRENIC Loader (see Section 9.2
Overview of FRENIC Loader) on the PC to edit the function code data and monitor the running status
of the inverter.
• Control via host equipment (COM ports 1 and 2)
Connecting the inverter to a PC, PLC, or other host equipment enables you to control the inverter as a
subordinate device from the host.
Besides the communications port (RJ-45 connector) shared with the keypad, the FRENIC-MEGA has
RS-485 terminals as standard. The connection via terminals facilitates multi-drop connection.
Protocols for managing a network including inverters include the Modbus RTU protocol (compliant to
the protocol established by Modicon Inc.) that is widely used in FA markets and the Fuji
general-purpose inverter protocol that supports the FRENIC-MEGA and conventional series of
inverters.
• Connecting the keypad to the COM port 1 automatically switches to the keypad protocol;
there is no need to modify the function code setting.
• When using FRENIC Loader, which requires a special protocol for handling Loader
commands, you need to set up some communication function codes accordingly.
For details, refer to the FRENIC Loader Instruction Manual.
• The COM port 2 supports only controls from host equipment, and not from the keypad or
FRENIC Loader.
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For details of RS-485 communication, refer to the RS-485 Communication User's Manual.
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