9.1 Overview on RS-485 Communication
9-4
9.1.3 Connection method
• Up to 31 inverters can be connected to one host equipment.
• The protocol is commonly used in the FRENIC series of general-purpose inverters, so programs for
similar host equipment can run/stop the inverter.
(The parameters specifications may differ depending on the equipment.)
• Fixed-length transmission frames facilitate developing communication control programs for hosts.
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For details of RS-485 communication, refer to the RS-485 Communication User's Manual.
Multi-drop connection using the RS-485 communications port 1 (for connecting the keypad)
For connecting inverters in multi-drop connection, use the branch adapters for multi-drop connection as
shown below.
Figure 9.1-1 Multi-drop Connection (Using the RJ-45 Connector)
• The RJ-45 connector (COM port 1) has power source pins (pins 1, 2, 7 and 8) exclusively
assigned to keypads. When connecting other devices to the RJ-45 connector, take care not
to use those pins. Use pins 4 and 5 only
. (For details, refer to 9.1.2 Terminal specifications
for RS-485 communications)
• When selecting additional devices to prevent the damage or malfunction of the control PCB
caused by external noises or eliminate the influence of common mode noises, be sure to see
section 9.1.4 "Communications support devices."
• The maximum wiring length must be 500 m.
• Use cables and converters meeting the specifications for proper connection. (Refer to [2]
"Requirements for the cable (COM port 1: for RJ-45 connector)" in Section 9.1.4
"Communications support devices."
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