Mitsubishi Electric ECOV-X37VA Manuel D'installation page 46

10-6. How to use MODBUS
10-6-1. Precautions for using MODBUS
• Do not connect a power supply to the terminal block for transmission lines (+, -, SG). If connected, the electronic parts will
burn out.
• Use shielded cables for transmission wiring. For information on recommended cables, refer to section 10-6-2.
Wiring using a multi-core cable with different types of transmission wires compromises correct transmission of signals and
results in a malfunction.
• When splicing transmission wires, make sure to splice the shielded cables as well.
• For details on the MODBUS
• Please contact the supplier for the MODBUS
10-6-2. RS485 communication specifications
The table below shows the RS485 communication specifications of the refrigerator.
Transmission signal
Electrical specifications
Communication protocol
Transmission system
Connection type
Maximum communication distance
Terminating resistor
Recommended cable
®
10-6-3. MODBUS wiring procedure
[1] Preparing the cables
Prepare cables for wiring. (Refer to section 10-6-2.)
[2] Turning off the power
Check that the power of each unit is turned off before the wiring work.
WT09614X03_GB
®
®
®
set-up, refer to the MODBUS
®
Interface Manual.
Item
Type
Number of pairs
Conductor resistance (20°C)
Insulation resistance (20°C)
Capacitance (1 Hz)
Characteristic impedance (100
kHz)
®
Interface Manual.
Specifications
RS-485 two-wire half-duplex transmission
RS-485 compliant
Modbus-RTU
Asynchronous
Daisy chain
1200 m
120 Ω, 1/2 W
Shielded cable
2 or 3
88 Ω/km or less
10000 MΩ-km or above
60 nF/km or less
110±10 Ω
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