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Appendix B - Adept DeviceNet
122 Adept SmartController User’s Guide, Rev. E
Figure B-5. Example of a Terminating Resistor Installation on a DeviceNet Bus
Power Supply and the DeviceNet Bus
The DeviceNet network allows distribution of power supplies on the network cable
system. Follow these general rules to achieve a safe and reliable operation:
• Use power supplies rated at 24V
• Minimize installation problems by using one power supply with sufficient
current to operate all the attached nodes. This must comply with the national
and international safety standards.
• Make sure that each power supply incorporates current limit protection.
• Make sure each power supply is temperature compensated.
• Provide over current protection for each segment of your DeviceNet cable
installation.
NOTE: Adept does not supply the 24V operating voltage for the
DeviceNet bus on the SmartController or any other Adept component.
Power Capabilities of a DeviceNet Cable System
A DeviceNet cable system has several power rating constraints. The cable type and the
length of the cable specify the maximum current on a cable. Thick and thin cable have:
• 24 VDC power rating
• Optional power-supply tabs
If the power supplies are equipped with Schottky diodes, the optional power supply tabs
must be protected from bus back-feeding of current among the power supplies on the bus.
We also recommended the use of fuse protection for every trunkline in the cable system.
WARNING: The DeviceNet specification requires that the
CAN_H and CAN_L signal lines tolerate voltages up to
18V. Since the supply voltage exceeds 18V, improperly
wiring the supply voltage to these signal lines may cause
permanent damage.
Pin 4 Pin 5
Terminating
Resistor