• Terminal 3: connect the A (+) signal of the RS485 line.
The RS485 line must be terminated with a 120 Ohm resistor on both ends. The resistor is already
integrated in Remote but must be activated by connecting together (jumper) terminals 1 and 2 of JO.
Warning: the RS485 line must be dedicated to the communication between Remote and GC315. No
other devices can be connected to the same line (neither master nor slave).
4.4.2.1 Connecting to the JO port of GC315
GC315 is equipped with an opto-isolated RS485 serial port, available on the JO connector. The
connection must therefore be:
The connections between terminals 1 and 2 (on both controllers) are required to insert the
termination resistors present inside the controllers themselves. To check for the proper wiring,
remove the power supply from both controllers and, with a multimeter, measure the resistance
between terminals 2 and 3 of JO connector (on one of the two controllers): it must be around 60 Ohm
(58…62).
Configure GC315 in this way:
• Parameter P.0471 (use of the serial port): “0-Modbus standard”.
• Parameter P.0472 (Modbus address): “1”.
• Parameter P.0473 (baud rate): “115200”.
• Parameter P.0474 (settings): “0-8 bit, no parity, 1 stop”.
• Parameter P.0475 (order of Modbus registers): “0-LSWF”.
Configure Remote in this way:
• Parameter P.0301 (connection mode with GC315): set to “0-RS485”.
• Parameter P.0302 (Modbus address of GC315): set to “1” (or to the same value as parameter
P.0472 of GC315).
• Parameter P.0303 (order of GC315 Modbus registers): set to “0-LSWF” (or to the same value
as parameter P.0475 of GC315).
• Parameter P.0473 (baud rate): set to “115200” (or to the same value as parameter P.0473 of
GC315).
• Parameter P.0474 (settings): set to “0-8 bit, no parity, 1 stop” (or to the same value as
parameter P.0474 of GC315).
The indicated baudrate (115200) allows the best performances for Remote. However, the maximum
selectable baud rate depends on the length of the RS485 line, and on the quality of the cable used. So,
select a baud rate suitable for the line length (the following figure can help in the selection).
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