Chapter 5: Communications
25
CANbus
Specific controller models comprise 1 port for CANbus networking purposes. Via this port,
you can create a decentralized control network of up to 63 controllers. This is sometimes
called a multi-master network. In such a network, CANbus enables inter-PLC data
exchange.
Unitronics’ CANbus control network is run by a separate isolated power supply that is not
part of the network power supply.
CANbus Specifications
Power Requirements: 24VDC (±4%), 40mA max. per unit
Galvanic Isolation between
CANbus and controller: Yes
Max. Network Cable Length:
1 Mbit/s -
500 Kbit/s -
250 Kbit/s -
125 Kbit/s -
100 Kbit/s -
50 Kbit/s -
20 Kbit/s -
25 m
100 m
250 m
500 m
500 m
1000 m
1000 m
Note: If you require cable lengths over 500 meters, contact technical support.
Wiring Considerations
• Use twisted-pair cable. DeviceNet® thick shielded twisted pair cable is
recommended.
• Network terminators: These are supplied with the controller. Place terminators at
each end of the CANbus network. Resistance must be set to 1%, 121Ω, 1/4W.
• Connect the ground signal to the earth at only one point, near the power supply.
• The network power supply need not be at the end of the network
• Maximum number of controllers in a network: 63
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