Fieldbus/Modbus Communication Cabling - Jetvent Fans JVEC-LP Installation Manual

Fieldbus/Modbus Communication Cabling
The controller is able to communicate using Modbus RTU (RS485) to JetVent Fans, Vacon Variable Speed Drives (VSDs), and
fieldbus sensors.
Devices must be connected in a daisy chain with the controller at the start of the chain. No star connections are
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allowed, and if a branch is required a Modbus repeater must be used.
IMPROPER WIRING CONFIGURATION
Maximum communication wiring length is 500m before a Modbus repeater is required.
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Separate conduit should be used for power and communications cable. Keep communications cable away from
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devices that generate EMC interference, such as powered antennas, transformers, contactors, and neon lights.
Low capacitance (<100 pF/m) twisted pair cable with shield and an impedance of approximately 120 ohms/m @
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100 kHz.
BELDEN 8761 (AWG22) is recommended for lengths under 500m
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BELDEN 8762 (AWG20) is recommended for lengths over 500m
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